There are two types of coupling between electronic circuits:
AC coupling means that only the AC parts of the signal will pass. For this normally a capacitor is used that connects the two circuits. The minimum value of the capacitor depends upon the lowest frequency (f) that has to be transmitted and the input/output impedance (R) of the two circuits. The approximate formula for the minimum capacity is C ~ 1/(R*f) with f = lowest frequency, R = in/output resistance Example: minimum frequency = 50Hz, in/output resistance = 10kOhm -> C ~ 2 uF (u = micro = 1/1000000). A usual value would be 2.2uF in this example. AC coupling is normally used for audio signals. For audio signals AC coupling has the advantage that unwanted DC shares in the signal are removed. For some AC processing circuits (e.g. amplifiers, filters) DC voltages are not allowed in the input signal. Therefore very often a capacitor can be found in the input stage of such circuits. DC coupling means that both DC and AC parts of a signal are transmitted. For control voltages (normally) only DC coupling can be used as even fixed voltages (e.g. coming from a manual control) have to be transmitted. In a module patch each A-100 module can be treated as an electronic circuit that is connected to another one. Consequently one has to take into consideration the type of coupling (AC or DC) between modules as the strict differentiation between AC and DC applications os softened for some A-100 modules. E.g. a VCA can be used to process audio signals (i.e. normally AC coupled signals) as well as slowly changing CV voltages (e.g. envelope or modulation amount). Therefore one needs to know if a VCA used is AC or DC coupled. Another example is a divider (e.g. A-115 or A-163) as even these module can be used to process audio or (slow) clock/gate signals. | |
 | Luckily it is not very complicated to switch between AC and DC coupling. All one has to do is to bride (i.e. short circuit) the capacitor in case of an AC coupled in/output. The left picture shows how the switch is connected in parallel to the AC coupling capacitor (the broken line resistor symbol represents the load to GND that is always available in each circuit as reference to GND). If AC coupling is required for a DC coupled in/output simply a capacitor has to be added. From the schematics it can be seen if an in/output is AC or DC coupled. We will add this information also to the users manual for modules that may be used for both types of coupling. For some circuits resp. modules changing from AC to DC coupling is not possible. E.g. the "old" VCAs A-130 and A-131 (those with CEM3381 or CEM3382) are AC coupled as the special CEM circuits cannot be DC coupled because of the internal negative reference voltage. The "new" VCAs A-130 and A-131 (those with CA3080) are DC coupled and can be used to process CV signals too. A list with the type of coupling for all modules in question will follow soon. For most of the modules the question about the type of coupling does not arise. E.g. all filters are AC coupled and all CV generating and processing modules (e.g. ADSR, LFO, slew limiter, Theremin, Ribbon controller, random voltage) are DC coupled. But for other modules the type of coupling is not obvious (e.g. VCA, divider, waveshaper). |
Saturday, October 25, 2014
Power Monitor Non Contact Diagram Circuit
This provides base current to T2 and it also conducts, pulling the collector to ground potential. As the collectors of T1 and T2 are connected to pin 2 of NAND gate N1 of the oscillator, the oscillator gets disabled when the transistors conduct. Capacitor C1 prevents rise of the collector voltage of T2 again during the negative half cycles. When the power fails, the electrical field around the equipment’s wiring ceases and T1 and T2 turn off. Capacitor C1 starts charging via R1 and preset VR and when it gets sufficiently charged, the oscillator is enabled and the piezobuzzer produces a shrill tone. Resistor R1 protects T2 from short circuit if VR is adjusted to zero resistance.The circuit can be easily assembled on a perforated/breadboard. Use a small plastic case to enclose the circuit and a telescopic antenna as aerial. A 9V battery can be used to power the circuit. Since the circuit draws only a few microamperes current in the standby mode, the battery will last several months. After assembling the circuit, take the aerial near the mains cable and adjust VR until the alarm stops to indicate the standby mode. The circuit can be placed on the equipment to be monitored close to the mains cable
Friday, October 24, 2014
Adjustable Symmetrical Power Supply Using LM317 and LM337
Using these types of regulators provide features such as low noise and low price in the market. It can be made operational even with few components used. The only disadvantage that it will impose is the poor conversion efficiency. With the output of 35 V to 5 V, the efficient ratio of the output power with the input power is less than 42%. This is the reason why the switching regulator became cheap recently although the number of external components to be connected is minimally increased. These regulators will work with better efficiency when used in case where current is more than 1A for more than 15 V and 0.4 A for less than 15 V from the power supply. Each regulator is adjusted for single positive and negative voltage output using the 10K ohms potentiometers RV1 & RV2. For dual outputs, a dual connected potentiometer RV3 is made to operate by switch S1. The visual indication on the voltmeter V1 is shown using the switch S2.
- R1-2=270ohms
- R3-4=2.2Kohms
- R5-6=10Kohms
- C1-5=100uF/63V
- C2-4=100nF/100V
- C3-8=10uF/25V
- C6-10=100uF/63V
- C7-9=100nF/100V
- RV1-2=10Kohms Lin.
- RV3=2X10Kohms Lin.
- IC 1=LM 317T
- IC 2=LM 337T
- D1-2=1N4001
- D3-4=1N4001
- L1-2=LED 3mm
- F1-2=1A slow Blow Fuse
- S1-2=2X ON-ON SW
- V1=0-30V DC Voltmeter
Thursday, October 23, 2014
Simple and hold circuit using op amp Circuits Diagram
Description
Circuit diagram
Sample and Hold circuit using uA741 opamp
Input and output waveforms.
Notes
- The circuit can be assembled on a vero board.
- Use +15V/-15V DC dual supply for powering the opamp.
- Capacitor C1 must have minimum leakage current possible and thats why a polyester capacitor is used here.
- Mount the IC uA741 on a holder.
- The type number of the MOSFET Q1 is not very significant here and so substitution is possible if BS170 is not available.
- BS170 is a 60V, 500mA n-channel enhancement mode MOSFET available in TO-92 package.
- Preset resistor R1 can be used for offset adjustments.
Monday, October 20, 2014
Adjustable Voltage and Variable Current Limiter Circuit Diagram
Saturday, October 18, 2014
MJ2955 for IC 78xx Boosting Regulator Current Diagram Circuit
IC 78xx series of voltage regulators are available with different current outputs, you can boost the available current output with this circuit. A power transistor is used to supply extra current to the load the regulator, maintaining a constant voltage. Currents up to 650mA will flow through the regulator, above this value and the power transistor will start to conduct, supplying the extra current to the load. This should be on an adequate heat sink as it is likely to get rather hot. Suppose you use a 12v regulator, 7812. The input voltage should be a few volts higher to allow for voltage drops. Assume 20 volts. Lets also assume that the load will draw 5amps. The power dissipation in the transistor will be Vce * Ic or (20-12)*8=40watt. It may keep you warm in the Winter, but you will need a large heatsink with good thermal dissipation. If you want to Boost the output current with a negative regulator, such as the 79xx series, then the circuit is similar, but an NPN type power transistor is used instead.
555 timer Electronic roulette wheel Diagram Circuit
Using a simple voltage controlled oscillator a 555 timer IC and 4017 counter/divider IC can be designed a very wonderful electronic roulette wheel game.
This electronic circuit is a simple version of an electronic roulette game and is based on the 4017 IC which is a 10 stage decade counter/divider. It is driven by another versatile IC 555 configured as a voltage controlled oscillator (VCO).
The 555 timer is connected as an astable multivibrator . When the S1 switch is pressed, the capacitor C3 gets charged, also at this point of time a constant stable clock is fed to the 4017 IC and the LEDs at its outputs light up in a cyclic manner producing a revolving effect. Adjusting the VR1 (variable resistor ) the speed of revolving effect can be varied .
When the S1 switch is released, the main supply is cut-OFF, C3 discharges and forces the freely running astable to gradually stretch and slow down the time period of its output pulses so that eventually the oscillations stop within a stipulated time. In response to these dying pulses the “rotation” of the LEDs connected to the output of IC 4017 also slow down gradually and stops to select a random score marked on the board.
This electronic roulette wheel game must be powered from a simple 9 volt DC power supply
Friday, October 17, 2014
Sub Woofer and Controller Circuit Diagram
all of sub woofers use a immense speaker driver in a immense box, with tuning vents & all the difficulties (& vagaries) that conventional operation entails. By conventional, I mean that the speaker & cabinet are operated as a resonant technique, using the Thistle-Small parameters to get a box which will (if everything works as it ought to) provide excellent performance.
The check methods I used are applicable to any combination, but in general I recommend either a single giant driver or a pair of (say) 300mm units. The next hurdle is the amplifier needed to drive the speaker. This is not trivial. If the selected driver has a sensitivity of 93dB / W @ one metre, then you can safely assume that the efficiency will be less than this below resonance, by a factor of possibly 6dB or more. In case you are used to driving a sub with 100W, this means that you have increased the power to 400W - although this is an over-simplification.
If they are to operate the sub from 60Hz (my aim from the outset), they will increase the power by 12dB for each octave, so if 20W is necessary at 60Hz, then at 30Hz this has increased to 320W, & at 15Hz, you will require over 5kW.
Fortunately, the reality is a tiny different, & 400W or so will be over sufficient for a powerful process, due chiefly to the fact that the energy content in the low bass region is not normally all that great. (Although some program material may have high energy content, in general this is not the case). The EAS process augments the existing process, which is allowed to roll off naturally - contrast this with the normal case, where a crossover is used to separate the low bass from the main process, so existing speaker capability is lost.
The controller is (actually very) simple, & the circuit is shown in Figure one. An input buffer ensures that the input impedance of the source does not affect the integrator performance, & allows summing of left & right channels without any crosstalk. The output provides a phase reversal switch, so that the sub can be properly phased to the remainder of the process. If the mid-bass disappears as you advance the level control, then the phase is wrong, so switch to the opposite position.
The integrators (U1B & U2A) include shelving resistors (R6 & R9), & the capacitor / resistor networks (C1-R4, C3-R7) be positive that signals below 20Hz are attenuated. In case you dont require to go that low, then the worth of the caps (or the resistors R4 & R7) can be reduced. I used four.7uF caps, & these are non-polarized electrolytic - a high value was needed to keep the impedance low to the integrators. I originally included the dual pot (VR1) to permit the upper frequency roll off to be set - however it does no such thing (as described above). The final output level is set with VR2, which may be left out if your power amp has a level control.
The unity gain range (using a 20k pot as shown) is from 53Hz to 159Hz. This ought to be sufficient for most systems, but if desired, the resistors (R5 & R8) can be increased in value to 22k, or you can select a bigger value pot. Using 22k resistors & the 20k pot will give a range from 36Hz to 72Hz.
The input must be a standard full range (or for a stampeded method, the whole low frequency signal). Do not use a crossover or other filter before the EAS controller. For final modification, and to integrate the method in to your listening room, I recommend the constant-Q equalizer. The final result using this is extraordinarily nice - I have flat in-room response to 20Hz!
The EAS method is surprisingly simple to set up with no instrumentation. Of coursework in case you have an SPL meter & oscillator you can also confirm the settings with measurements. Keep in mind that the room acoustics will play havoc with the results, so unless you require to drag the whole method outside, setting by ear might be the simplest. Even in case you did get it exactly right in an anechoic surroundings, this would alter one time it was in your listening room anyway.
It takes a small experimentation to get right, but is surprisingly simple to do. When properly set, a check track (or bass guitar) ought to be smooth from the highest bass note to the lowest, with no gross peaks or dips. Some are inevitable because of room resonances & the like, but you will discover a setting that sounds "right" with small difficulty.
I measured 80dB SPL at one meter in my workshop (sub-woofer perched on a chair in more or less the middle of the space) with at 25Hz & 70W. This improved dramatically when the unit was installed in the listening room, but as I said earlier, there is usually not a lot recorded below around 35Hz. The longest pipe on the organ is usually about 16Hz, but larger pipes still may be used. It was found necessary to cease group of diapasons (able to 8Hz) in the famous Sydney Town Hall organ because when they were used, the very low frequency caused building destroy.
Table 4 W Zener Diodes 1W 3W 5W 5 W and 6 Watts
Table 0.5 Watt Zener Diodes
1N746 – 3V3
1N747 – 3V6
1N748 – 3V9
1N749 – 4V3
1N750 – 4V7
1N751 – 5V1
1N752 – 5V6
1N753 – 6V2
1N754 – 6V8
1N755 – 7V5
1N756 – 8V2
1N757 – 9V1
1N758 – 10V
1N962 – 11V
1N759 – 12V
1N964 – 13V
1N965 – 15V
1N966 – 16V
1N967 – 18V
1N968 – 20V
1N969 – 22V
1N970 – 24V
1N971 – 27V
1N972 – 30V
1N973 – 33V
1N974 – 36V
1N975 – 39V
1N976 – 43V
1N977 – 47V
1N978 – 51V
1N979 – 56V
1N980 – 62V
1N981 – 68V
1N982 – 75V
1N983 – 82V
1N984 – 91V
1N985 – 100V
Table 1 Watt Zener Diodes
1N4728 – 3V3
1N4729 – 3V6
1N4730 – 3V9
1N4731 – 4V3
1N4732 – 4V7
1N4733 – 5V1
1N4734 – 5V6
1N4735 – 6V2
1N4736 – 6V8
1N4737 – 7V5
1N4738 – 8V2
1N4739 – 9V1
1N4740 – 10V
1N4741 – 11V
1N4742 – 12V
1N4743 – 13V
1N4744 – 15V
1N4745 – 16V
1N4746 – 18V
1N4747 – 20V
1N4748 – 22V
1N4749 – 24V
1N4750 – 27V
1N4751 – 30V
1N4752 – 33V
1N4753 – 36V
1N4754 – 39V
1N4755 – 43V
1N4756 – 47V
1N4757 – 51V
1N4758 – 56V
1N4759 – 62V
1N4760 – 68V
1N4761 – 75V
1N4762 – 82V
1N4763 – 91V
1N4764 – 100V
Table 5 Watt Zener Diodes
1N5333 – 3V3
1N5334 – 3V6
1N5335 – 3V9
1N5336 – 4V3
1N5337 – 4V7
1N5338 – 5V1
1N5339 – 5V6
1N5340 – 6V0
1N5341 – 6V2
1N5342 – 6V8
1N5343 – 7V5
1N5344 – 8V2
1N5345 – 8V7
1N5346 – 9V1
1N5347 – 10V
1N5348 – 11v
1N5349 – 12v
1N5350 – 13v
1N5351 – 14V
1N5352 – 15V
1N5353 – 16V
1N5354 – 17V
1N5355 – 18V
1N5356 – 19V
1N5357 – 20V
1N5358 – 22V
1N5359 – 24V
1N5360 – 25V
1N5361 – 27V
1N5362 – 28V
1N5363 – 30V
1N5364 – 33V
1N5365 – 36V
1N5366 – 39V
1N5367 – 43V
1N5368 – 47V
1N5369 – 51V
Table of zener diodes BZX line
Line BZX79 .5 Watt of power voltage of 2.4 Volts 68
Line BZV60 .4 Watts power voltage of 2.4 V to 68 Volts
Line BZT03 power of 3.25 Watts 7.5 V voltage to 270 Volts
Line BZW03 power of 6 Watts 7.5V voltage to 270 Volts
VOLTAGE VOLTS WATTS
1N746A BZX79C3V3 3,3 0,5
1N747A BZX79C3V6 3,6 0,5
1N748A BZX79C3V9 3,9 0,5
1N750A BZX79C4V7 4,7 0,5
1N751A BZX79C5V1 5,1 0,5
1N752A BZX79C5V6 5,6 0,5
1N753A BZX79C6V2 6,2 0,5
1N754A BZX79C6V8 6,8 0,5
1N755A BZX79C7V5 7,5 0,5
1N756A BZX79C8V2 8,2 0,5
1N757A BZXT9C9V1 9,1 0,5
1N758A BZX79C10 10 0,5
1N962B BZX79C11 11 0,5
1N759A BZXT9C12 12 0,5
1N964B BZX79C13 13 0,5
1N965B BZX79C15 15 0,5
1N966B BZX79C16 16 0,5
1N967B BZX79C18 18 0,5
1N968B BZX79C20 20 0,5
1N969B BZX79C22 22 0,5
1N970B BZX79C24 24 0,5
1N971B BZX79C27 27 0,5
1N972B BZX79C30 30 0,5
1N973B BZX79C33 33 0,5
1N4728A BZX81C3V3 3,3 1
1N4729A BZX81C3V6 3,6 1
1N4730A BZX81C3V9 3,9 1
1N4731A BZX81C4V3 4,3 1
1N4732A BZX81C4V7 4,7 1
1N4733A BZX81C5V1 5,1 1
1N4734A BZX81C5V6 5,6 1
1N4735A BZX81C6V2 6,2 1
1N4736A BZX81C6V8 6,8 1
1N4737A BZX81C7V5 7,5 1
1N4738A BZX81C8V2 8,2 1
1N4739A BZX81C9V1 9,1 1
1N4740A BZX81C10 10 1
1N4741A BZX81C11 11 1
1N4742A BZX81C12 12 1
1N4743A BZX81C13 13 1
1N4744A BZX81C15 15 1
1N4745A BZX81C16 16 1
1N4746A BZX81C18 18 1
1N4747A BZX81C20 20 1
1N4748A BZX81C22 22 1
1N4749A BZX81C24 24 1
1N4750A BZX81C27 27 1
1N4751A BZX81C30 30 1
1N4752A BZX81C33 33 1
VOLTS 0,5W 1W 5W
2,4 1N5221B ———— ———–
2,7 1N5223B ———— ———–
3.0 1N5225B ———— ———–
3.3 1N5226B 1N4728A 1N5333B
3,6 1N5227B 1N4729A 1N5334B
3,9 1N5228B 1N4730A 1N5335B
4,3 1N5229B 1N4731A 1N5336B
4,7 1N5230B 1N4732A 1N5337B
5,1 1N5231B 1N4733A 1N5338B
5,6 1N5232B 1N4734A 1N5339B
6,0 1N5233B ————- 1N5340B
6,2 1N5234B 1N4735A 1N5341B
6,8 1N5235B 1N4736A 1N5342B
7,5 1N5236B 1N4737A 1N5343B
8,2 1N5237B 1N4738A 1N5344B
8,7 ———– ————- 1N5345B
9,1 1N5239B 1N4739A 1N5346B
10 1N5240B 1N4740A 1N5347B
11 1N5241B ————- 1N5348B
12 1N5242B 1N4742A 1N5349B
13 1N5243B 1N4743A 1N5350B
14 ———– ————- 1N5351B
15 1N5245B 1N4744A 1N5352B
16 1N5246B 1N4745A 1N5353B
18 1N5248B 1N4746A 1N5355B
20 1N5250B 1N4747A 1N5357B
22 1N5251B 1N4748A 1N5358B
24 1N5252 1N4749A 1N5359B
27 1N5254B 1N4750A 1N5361B
28 ———– ————- 1N5362B
30 1N5256B 1N4751A 1N5363B
33 1N5257B 1N4752A 1N5364B
36 1N5258B 1N4753A 1N5365B
39 1N5259B 1N4754A 1N5366B
43 1N5260B 1N4755A 1N5367B
47 1N5261B 1N4756A 1N5368B
51 1N5262B 1N4757A 1N5369B
56 1N5263B 1N4758A 1N5370B
62 1N5265B 1N4759A 1N5372B
68 1N5266B 1N4760A 1N5373B
75 1N5267B 1N4761A 1N5374B
82 1N5268B 1N4762A 1N5375B
91 1N5270B 1N4763A 1N5377B
100 ———– 1N4764A 1N5378B
120 ———– ————- 1N5380B
150 ———– ————- 1N5383B
200 ———– ————- 1N5388B
Monday, October 13, 2014
Motorized Video Camera Mount circuit description and parts
Introduction
This article describes a motorized, waterproof mount for a miniature video camera. If a suitable waterproof camera is used, this unit can be used outdoors.
Theory
The camera rotator circuit uses a 2716 EPROM to store a table of logic values that control the motor driver (H-bridge) circuit. The EPROM data is shown in the schematic. By using the EPROM, a large number of discrete gates are eliminated. The logic table is designed to allow the motor to turn clockwise until the clockwise limit sensor is activated. The same operation happens with counter clockwise rotation and the counter clockwise limit sensor.
Inputs to the EPROM come from the limit sensors and the two control switch directions. Outputs go to the four H-bridge transistor gates. The control switch signals are buffered through the 7400 quad NAND gate, this allows for a long control wire. All of the input values are active in the low state.
The H-bridge array consists of two N-channel MOSFETs and two P-channel MOSFETs. Diagonal pairs of transistors are turned on to move the motor one way or the other. If all of the transistors are off, the motor does not move. Note that the P channel transistors turn on with a 0 logic output level and the N channel transistors turn on with a 1 logic output level.
There are several disallowed output states, if three or four transistors were to be turned on, the transistors would go up in smoke. Dont do this. If the EPROM is programmed correctly, this should never happen.
The voltage regulator produces 5 volts for running the logic ICs and the motor. A better H-bridge driver circuit (or IC) could be used if higher motor currents are needed, this one was sufficient, simple to build, and easy to find parts for
.Note that a much simpler version of this circuit could be made by using a cross-wired center off DPDT direction switch and mechanical limit sensor switches in series with the motor power wires and with diodes across the switches. This circuit has fewer moving parts, and the sensors can fit into a smaller space than switches. The all solid state design should also last longer.
Specifications
- Degrees of rotation: 350 (depending on hall effect sensor locations)
- Operating Voltage: 12V D.C.
- Operating Current: approx. 500ma when rotating and 30ma idle.
- Remote Control Interface: 4 wire shielded cable
- Height: 16 inches
- Width: 2-1/4 inches
Electrical Construction
There are two circuit boards in this project, both were hand-wired. The main board houses the logic circuitry and the motor H-driver VMOS FET array. It was constructed on a solderable bread-board.The hall effect sensor array was built on a piece of copper PC board. The board was cut to a C shape and holes were drilled in the ends so that the board could be screwed to the motor mount tabs. The two hall effect sensors were glued to the PC board with epoxy glue. Be sure to secure the wire coming from the sensor board with some form of strain relief. Plastic wire ties are suitable for this job.
Both sensors are located an equal distance from the center of the motor shaft. Other sensor board components were hand-wired to the sensors. The sensor board can be seen in the photo, it is mounted on the top of the motor where the shaft exits the motor case. The D-shaped aluminum block has a small, but powerful magnet glued to the side that passes directly over the hall effect sensors. The magnets pass within about 1/8 inch over the sensors.
Mechanical Construction
This project involves a fair amount of mechanical work. The tube that holds the camera, electronics, and motor was fabricated with Schedule 40 ABS black pipe. The longer portion (top) of the pipe is stationary, and should be secured to an external mount with hose clamps or other mounts. The top portion consists of a cap on top, a long tube with room for the motor and logic board, and an ABS pipe sleeve. Glue the sleeve to the bottom of the long pipe. Dont get any glue on the bottom half of the sleeve. The top cap can be connected to the upper pipe by drilling a small hole through the cap pipe, and installing a small stainless steel screw. A small hole is drilled through the upper pipe, this allows the video camera and motor control wires to exit the assembly. When the assembly is complete, seal the wires where they exit with Silicone caulk.The small, lower portion of the pipe houses the video camera. The top inch of the lower portion should be evenly filed around the outside so that it can be fitted easily into the top portions sleeve. Keep filing until the lower portion of the pipe spins easily in the sleeve. A hole needs to be cut in the lower portion to house the camera. This can be done by drilling small holes, then filing the opening until the camera fits snugly. The hole should be large enough to allow the camera to be adjusted up and down. I secured my camera in the lower assembly with blue packing foam. A pipe cap covers the bottom of the lower assembly.
The cameras wire should pass through the inside of the tube, put a few loops of extra wire on the camera side. It is important to verify that the wire does not get hung up on any objects in its path.
Water flow should be considered, if the assembly is built correctly, it should be able to withstand blowing rain without getting the electronics wet. A small hole should be drilled in the lower pipe cap to allow any moisture that condenses inside to escape.
Several metal pieces need to be fabricated. A small bracket is needed to connect the motor mount to the side of the upper tube. The size of the bracket depends on the motor that is used. The motor shaft should be exactly centered in the tube when the mount is complete.
The shaft mount piece is a D-shaped chunk of aluminum, a hole was drilled to fit the motor shaft, a side hole was drilled and tapped to hold a set-screw for securing the mount to the shaft. Two mount holes were drilled and tapped into the mount, screws pass through the lower pipe into the mount. The magnet is glued to the bottom of the shaft mount, it should pass right over the hall effect sensors. Test the magnet on the hall effect sensors before gluing them in place, the sensors only respond to one side (pole) of the magnet.
Alignment
Make sure that the camera wire does not get hung up on the insides of the camera, this is achieved by adjusting the length so that the wire has some slack when it is at either extreme of the movement. It is advisable to round any sharp edges that are in the area where the video wire rotates.The hall effect sensors should be checked out, make sure that the magnet changes the logic state on both sensor outputs when it passes over them.
Use
Turn the switch to CCW, the camera should rotate couter clockwise until the limit is sensed. Turn the switch to CW, the camera should rotate clockwise until the other limit is reached. Turn the switch off, the camera should stand still.Parts
This project was built with surplus parts. The motor is a 12 Volt gear reduction unit made by Globe. The electronic components can be found at Digi Key (1-800-DIGI-KEY).The camera is a model GM300K-N from Resources Unlimited.
readmore at: http://english.cxem.net/rf/rf30.php
Signal Amplifier For TV explanation Charecteristics and circuit
It is connected between the antenna and the input of your receiver and boosts the signals by up to 20 dB, thus making it possible to receive even the weakest signals.
  Dimensions (4,3cm x 5,4cm) |
| Technical Specifications -Characteristics Frequency response: 40 - 900 MHz Gain: . 20 dB Maximum output level: 90 uV Input - output impedance: 75 ohm |
The circuit is built around a single transistor a UHF low signal device, the BFW 92. This transistor can operate in frequencies as high as 1.6 GHz, and has a gain of 23 dB. The signal from the antenna is applied to the input of the circuit and through C5 is fed to the base of the transistor. It is amplified and from the collector of the BFW 92 through C2 and C1 is taken to the input of the radio or TV receiver.
The circuit operates off a small 9 V battery which, because of the very low power consumption of the circuit, is going to last for a very long time.
Construction
First of all let us consider a few basics in building electronic circuits on a printed circuit board. The board is made of a thin insulating material clad with a thin layer of conductive copper that is shaped in such a way as to form the necessary conductors between the various components of the circuit. The use of a properly designed printed circuit board is very desirable as it speeds construction up considerably and reduces the possibility of making errors. Smart Kit boards also come pre-drilled and with the outline of the components and their identification printed on the component side to make construction easier. To protect the board during storage from oxidation and assure it gets to you in perfect condition the copper is tinned during manufacturing and covered with a special varnish that protects it from getting oxidised and also makes soldering easier.
Soldering the components to the board is the only way to build your circuit and from the way you do it depends greatly your success or failure. This work is not very difficult and if you stick to a few rules you should have no problems. The soldering iron that you use must be light and its power should not exceed the 25 Watts. The tip should be fine and must be kept clean at all times. For this purpose come very handy specially made sponges that are kept wet and from time to time you can wipe the hot tip on them to remove all the residues that tend to accumulate on it. DO NOT file or sandpaper a dirty or worn out tip. If the tip cannot be cleaned, replace it. There are many different types of solder in the market and you should choose a good quality one that contains the necessary flux in its core, to assure a perfect joint every
time.
DO NOT use soldering flux apart from that which is already included in your solder. Too much flux can cause many problems and is one of the main causes of circuit malfunction. If nevertheless you have to use extra flux, as it is the case when you have to tin copper wires, clean it very thoroughly after you finish your work. In order to solder a component correctly you should do the following:
- Clean the component leads with a small piece of emery paper.
- Bend them at the correct distance from the component’s body and insert the component in its place on the board.
- You may find sometimes a component with heavier gauge leads than usual, that are too thick to enter in the holes of the p.c. board. In this case use a mini drill to enlarge the holes slightly. Do not make the holes too large as this is going to make soldering difficult afterwards.
- Take the hot iron and place its tip on the component lead while holding the end of the solder wire at the point where the lead emerges from the board. The iron tip must touch the lead slightly above the p.c. board.
- When the solder starts to melt and flow, wait till it covers evenly the area around the hole and the flux boils and gets out from underneath the solder. The whole operation should not take more than 5 seconds. Remove the iron and leave the solder to cool naturally without blowing on it or moving the component. If everything was done properly the surface of the joint must have a bright metallic finish and its edges should be smoothly ended on the component lead and the board track. If the solder looks dull, cracked, or has the shape of a blob then you have made a dry joint and you should remove the solder (with a pump, or a solder wick) and redo it.
- Take care not to overheat the tracks as it is very easy to lift them from the board and break them.
- When you are soldering a sensitive component it is good practice to hold the lead from the component side of the board with a pair
of long-nose pliers to divert any heat that could possibly damage the component.
- Make sure that you do not use more solder than it is necessary as you are running the risk of short-circuiting adjacent tracks on the board, especially if they are very close together.
- When you finish your work, cut off the excess of the component leads and clean the board thoroughly with a suitable solvent to
remove all flux residues that may still remain on it.
The project is a very easy one, as the components which form the circuit are very few and their outlines have been clearly stencilled on the board for you. The only unusual thing is that the transistor must be soldered from the copper side of the board. This is, however, common with UHF devices and is usually done to avoid the introduction of stray capacitances between the transistor’s leads that could possibly alter the behaviour of the circuit. Be careful to make good joints and try to keep the component leads as short as possible because of the very high frequencies involved. Solder first of all the pins and the resistors. The coils are supplied ready to be soldered on the printed circuit and you
should take care not to deform them in the process. Place then the capacitors and solder the diodes carefully trying to avoid overheating them and making sure that they are correctly aligned. Solder the transistor in its place, after you have finished soldering the other components, to avoid overheating it, and be careful to align it according to the diagram included in the instructions. (The lettering on the transistor body should be facing away from the copper). The input of the circuit is at point 4 and ground and the output at point 1 and ground. The battery is connected using the battery clip supplied at points 2 (-) and 3 (+), and is a miniature 9 V one, alkaline if you prefer. For best performance and to avoid unwanted interference during operation it is recommended to place the circuit in a small metal box, and use suitable connectors mounted on the box for the external connections. You can use a box large enough to house the amplifier and the battery or you can use an external power supply, but remember to use a FEED THROUGH capacitor on the positive supply line, where it passes through the metal box. If you plan to use the amplifier for both VHF and UHF TV reception you should use a common VHF/UHF mixer before the amplifier’s input.
R2 = 1,5 KOhm (brown, green, red)
R3 = 270 Ohm (red, violet, brown)
R4 = 82 KOhm (gray, red, orange)
C1,C5 = 100pF (ceramic)
C2,C3 = 1nF (ceramic)
C4 = 2,2pF (ceramic)
D1,D2 = 1N4148 diode
Transistor = BFR90, BFR91, BFW92
Misc = PCB, 6pins, solder, 9V battery clip
Sunday, October 5, 2014
regulator 3A switching circuit and explanation
When compared to linear voltage regulators the switching voltage regulators are much power efficient. In the case of linear voltage regulators the difference between the input and output voltage is just wasted and for switching regulators there is almost no such wastage and that’s why the switching regulators have great power efficiency ranging up to 85% . In simple words, the switching regulator operates by taking small bits of energy from the input voltage source and then transferring it to the output with the help of a solid state switch and a control circuitry. Since the switching element is either fully open or closed at any moment, no energy is wasted across it. The control circuit controls the duty cycle of the solid state switch which in turn determines rate at which energy is transferred to the output.
The electronic circuit given here is of a simple and low cost switching regulator using the IC LM317 that can deliver up to 3A of current. The input voltage range of this circuit is between 8 to 35V DC and the output voltage can be adjusted between 1.8 to 32V DC. The output voltage can be adjusted by using the POT R4.
Circuit diagram.
Notes.
- Assemble the circuit on a good quality PCB.
- C1 must be a solid tantalum capacitor.
- Transistor T1 and IC1 require heat sinks.
- L1 can be a 600uH inductor.
1999 Land Rover Defender Td5 Wiring Diagram and Electrical System
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Wednesday, October 1, 2014
Simple Function Generator Circuit Triangle and Square Wave Generator Circuit
Circuit diagram for the simple function generator circuit. Triangle wave and square wave generator circuit.
Tuesday, September 23, 2014
Adjustment power supply values 1 25 15V Max current 0 5 amp circuit
This is power supply that have Voltage output fine the value has 1.25-15V. From by Output current that be valuable about 0.5 amp that 12V and 0.2 amp that 15V.
When Volt , from 220V houses reach transformer. It will modify Volt 220V to be 18VAC already to change rectifier circuit. Which D1, D2, C1 and R1 wasp be Full wave rectifier circuit. For modify DCV to ACV to a signal DCV. It make get a signal DCV that have voltage at pin 3 of IC1 be 20V. From that time DCV signal this reach fight DC Regulator circuit. Which use IC number LM317.
This circuit will perform to maintain one’s position Voltage smoothly. Which level output voltage at get this will go out the way pin 2 of IC1. By have capacitors C2 be voltage filter in order that voltage output level of the circuit is will high class modify to follow fining. The performing fee withstands VR1 there.
from:eleccircuit.com
Monday, September 22, 2014
Changing between AC and DC coupling
Changing between AC and DC coupling
Horn siren use the IT and OT transformer
Basically siren on a police patrol car and an ambulance use electronic circuit connected to the DC current. When the switch is pressed, the siren sounds immediately come out.For those of you who own a car, or any motor you can also create a similar horn. Placement was also very practical. And if you want the flashing lights can add your own. In a series of above do not use flashing lights as the sirens sound.
R1 = 47K
R2 = 200R
C1 = 0,02uF
C2 = 50uF 16V
C3 = 0,005uF
T1 = 2SB178 PNP transistor
S1 = Push button switch
G1 = 6-12V battery
TR1 , IT transformer is reversed. used a two-legged.
TR2 , OT output transformer OT240
How to use it is to put the above series into a box. Adjust the size to be more practical. Then insert the cable of a car or motorcycle battery voltage as described above that is 6-12 V battery into the plug. In accordance with their respective poles.Three feet of IT transformer wrapped so as not to stick to the body of the car or motorcycle. Cover with insulation that is resistant to water. Then try if already issued a siren sounds and if so, ready for use.
With Time Delay High And Low Voltage Cut Off
Overview
The power line fluctuations and cut-offs cause damages to electrical appliances connected to the line. It is more serious in the case of domestic appliances like fridge and air conditioners. If a fridge is operated on low voltage, excessive current flows through the motor, which heats up, and get damaged.
The under/over voltage protection circuit with time delay presented here is a low cost and reliable circuit for protecting such equipments from damages. Whenever the power line is switched on it gets connected to the appliance only after a delay of a fixed time. If there is hi/low fluctuations beyond sets limits the appliance get disconnected. The system tries to connect the power back after the specific time delay, the delay being counted from the time of disconnection. If the power down time (time for which the voltage is beyond limits) is less than the delay time, the power resumes after the delay: If it is equal or more, then the power resumes directly.
This circuit has been designed, built and evaluated by me to use as a protector for my home refrigerator. This is designed around readily available semi-conductor devices such as standard bipolar medium power NPN transistor (D313/SL100/C1061), an 8-pin type 741 op-amp and NE555 timer IC. Its salient feature is that no relay hunting is employed. This draw back is commonly found in the proctors available in the market.
The complete circuit is consisting of various stages. They are: - Dual rail power supply, Reference voltage source, Voltage comparators for hi/low cut offs, Time delay stage and Relay driver stage. Lets now look at the step-by-step design details.
Dual rail power supply.
This is a conventional type of power supply as shown in Figure 1. The power is applied through the step-down transformer (230/12-0-12V/500mA). The DC proportional to the charging input voltage is obtained from bridge rectifier. Two electrolytics are there to bypass any spikes present. Bridge is capable of handling currents up to 1 Amp.
Output is given by: -
V(out) = 0.71 X V (secondary)
= 0.71 X 24V
= 17.04 V
(This equation is similar for the negative rail as well)
Circuit diagram
Low voltage cut off op-amp
Figure 2 shows the use of very common and easily available op-amp 741 as a comparator. The op-amp is available in TO-5 and DIP type packing.
Circuit diagram
In this ckt the zener diode D1 and it’s associated resistor R1 are connected to the non-inverting terminal (+ve) of 741 to give the suitable reference voltage. The DC voltage from the sensor is given to the inverting (-ve) terminal through pre-set R2.This is used to set the input level.
When the sensor input is less than Zener voltage the output from the Op-amp remains high and when it is greater than Zener voltage the output goes low. When the sensing voltage is equal to Zener voltage the output of the op-amp is approximately zero.
This phenomenon is used as a decision for switching the relay and to give cutoff in a low voltage situation.
High voltage cut off op-amp
Here the op-amp is used as a inverted amplifier. See Figure 3.Zener and resistor network gives reference voltage to the inverting terminal (-ve) of op-amp. Sensing voltage derived through the 10 K pre-set is given to the non- inverting (+ve) terminal and this sets the high level cut.
When the input DC from the sensor is less than Zener voltage the output of the op-amp is low and vice-versa. When the input DC voltage is equal to the zener voltage, the op-amps output is approximately zero.
Circuit diagram
Time delay
I’ve selected the 555 timer due to following reasons.
1. Timing from microseconds through hours.
2. Ability to operate from wide range of supply voltages.
3. High temperature stability.
4. Easily Available.
5. Its triggering circuit is quite sensitive.
This is basically a monostable. The external timing capacitor C2 is held initially discharged by the timer. The circuit triggers upon receiving a pulse to its pin 2 when the level reaches 1/3 Vcc. Once triggered., the circuit will remain in that state until the set time is elapsed or power to the circuit cuts off. The delayed period in seconds is 1.1 C2.R1 where R1 is in megohms and C2 is in microfarads. In practice, R1 should not exceed 20 M. If you use an electrolytic capacitor for C2, select a unit for low leakage. The time delay may have to be adjusted by varying R1 to compensate for the wide tolerance of electrolytics.
Circuit diagram
Relay Driver
The output from the voltage level detectors cannot directly drive the relay and hence the relay driver is used.
Circuit diagram
The Complete Circuit
Circuit diagram
Under normal operating conditions i.e. when the input voltage is between maximum and minimum limit the output from the both the comparators are low. The transistor Q1 is OFF and the relay is in de-energized (pole connected to N/C pin) state and the output is obtained.
When the input voltage is below or above the limits set by the pre-sets R8 or R9, the output of the Op-Amps goes either low or high and diodes D1 or D2 would be forward biased depending on the situation. Transistor Q1 switches ON and the flow of current from collector to emitter energizes the relay and the output is cutoff.
A small amount of hystersis has been added via feed back resistors R10 & R11 so that the relay turns on when the level falls to a particular value but does not turn again until it raises a substantial amount above this value. Other wise the relay contacts will frequently turn on/off and produce chattering.
Construction Hints
1) I used a piece of varoboard, which has copper strips on one side to mount the components, and housed the entire circuit and the transformer in a discarded ATX PC power supply box.
2) An autotransformer has been used to set the limits. Set the output of the autotransformer to 250V AC and connect it to the primary of transformer T1 (see Figure 1). Then adjust the pre-set R9 such that relay just energizes. This is the high limit. Next set the output of the autotransformer to 200V AC and adjust the pre-set R8 such that the relay energizes. Please note that these are my preferred limits but you may select any range from say 170 to 270V AC.
3) A neon with a suitable resistor could be connected between the AC supply lines as an ON indicator. Alternatively, LED with a current limiting resistor could be connected between the relay coil so when the relay is energized LED will indicate the situation.
Car Battery Charger description and circuit diagram
This charger will quickly and easily charge most any lead acid battery. The charger delivers full current until the current drawn by the battery falls to 150 mA. At this time, a lower voltage is applied to finish off and keep from over charging. When the battery is fully charged, the circuit switches off and lights a LED, telling you that the cycle has finished.
Circuit diagram
Parts
R1 500 Ohm 1/4 W Resistor
R2 3K 1/4 W Resistor
R3 1K 1/4 W Resistor
R4 15 Ohm 1/4 W Resistor
R5 230 Ohm 1/4 W Resistor
R6 15K 1/4 W Resistor
R7 0.2 Ohm 10 W Resistor
C1 0.1uF 25V Ceramic Capacitor
C2 1uF 25V Electrolytic Capacitor
C31000pF 25V Ceramic Capacitor
D1 1N457 Diode
Q1 2N2905 PNP Transistor
U1 LM350 Regulator
U2 LM301A Op Amp
S1Normally Open Push Button Switch
MISC Wire, Board, Heatsink For U1, Case, Binding Posts or Alligator Clips For Output
Notes
1. The circuit was meant to be powered by a power supply, which is why there is no transformer, rectifier, or filter capacitors on the schematic. There is no reason why you cannot add these.
2. A heatsink will be needed for U1.
3. To use the circuit, hook it up to a power supply/plug it in. Then, connect the battery to be charged to the output terminals. All you have to do now is push S1 (the "Start" switch), and wait for the circuit to finish.
4. If you want to use the charger without having to provide an external power supply, use the following circuit.
C1 6800uF 25V Electrolytic Capcitor
T1 3A 15V Transformer
BR1 5A 50V Bridge Rectifier 10A 50V Bridge Rectifier
S1 5A SPST Switch
F1 4A 250V Fuse
5. The first time you use the circuit, you should check up on it every once and a while to make sure that it is working properly and the battery is not being over charged.
Sunday, September 21, 2014
Thermistor Temperature Monitor Circuit and explanation
Thermistor Temperature Monitor Circuit and explanation
This sensor circuit uses an ordinary NTC thermistor with a resistance of 47k at room temperature. A suitable part from Maplin Electronics is FX42V. The circuit is set in balance by adjusting the the 47k potentiometer. Any change in temperature will alter the balance of the circuit, the output of the op-amp will change and energize the relay. Swapping the position of the thermistor and 47k resistor makes a cold or frost alarm.
At room temperature (25 degrees Celsius) a 47k NTC thermistor resistance is approximately 47k. The non-inverting op-amp input will then be roughly half the supply voltage, adjusting the 47k pot should allow the relay to close or remain open. To calibrate the device, the thermistor ideally needs to be at the required operating temperature. If this is for example, a hot water tank, then the resistance will decrease, one way to do this is use a multimeter on the resistance scale, read the thermistors resistance and then set the preset so that the circuit triggers at this temperature.
Please note that if the temperature then falls, the relay will de-energize. If the environment temperatures changes rapidly, then the relay may chatter, as there is no hysteresis in this circuit.
Hysteresis, allows a small amount of "backlash" to be tolerated. With a circuit employing hysteresis, there will be no relay chatter andthe circuit will trigger at a defined temperature and require a different temperature to return to the normal state. Hysteresis can be applied to the circuit using feedback, try a 1 Mega resistor between op-amp output, pin 6 and the non-inverting input pin 2 to give the circuit hysteresis.
Without offset null adjustment, the output of the 741 IC will be around 2 Volts (quiescent) swinging to nearly full supply when triggered. The 4.7k and 1k resistor form a potential divder so that under quiescent conditions the transistor will be off. Quiescent or steady state means no signal, or in this case (when the temperature does not cause the output to swing to full voltage).
Source: Temperature Monitor
Monday, September 15, 2014
Control Switch for Fan and Air Conditioner
Control Switch for Fan and Air-Conditioner Circuit Diagram
Assemble the schema on a general-purpose PCB and enclose in a suitable case. Fix the unit onto the switchboard. Use relays RL1 and RL2 with proper contact ratings. The current rating depends on the load that you are going to control.
