Wiring circuit

Showing posts with label controller. Show all posts

Friday, October 24, 2014

PWM Dimmer Motor Speed Controller

This is yet another project born of necessity. Its a simple circuit, but does exactly what its designed to do - dim LED lights or control the speed of 12V DC motors. The circuit uses PWM to regulate the effective or average current through the LED array, 12V incandescent lamp (such as a car headlight bulb) or DC motor. The only difference between the two modes of operation is the addition of a power diode for motor speed control, although a small diode should be used for dimmers too, in case long leads are used which will create an inductive back EMF when the MOSFET switches off.

Photo of Completed PWM Dimmer/Speed Control

The photo shows what a completed board looks like. Dimensions are 53 x 37mm, so its possible to install it into quite small spaces. The parts used are readily available, and many subsitiutions are available for both the MOSFET and power diode (the latter is only needed for motor speed control). The opamps should not be substituted, because the ones used were chosen for low power and their ability to swing the output to the negative supply rail.

Note that if used as a motor speed controller, there is no feedback, so motor speed will change with load. For many applications where DC motors are used, constant speed regardless of load is not needed or desirable, but it is up to you to decide if this will suit your needs.

Description

First, a description of PWM is warranted. As the pot is rotated clockwise, the input voltage changes linearly with rotation. At first, the voltage is such that the comparator output is just narrow spikes, which turn the MOSFET on for a very short period. Average current is low, so connected LEDs will be quite dim, or a motor will run (relatively) slowly. As the input voltage coming from the pot increases, the MOSFET is on for longer and longer, so increasing power to the load.

Figure 1 - PWM Waveform Generation

Figure 1 shows how the PWM principle works. The red trace is the triangle wave reference voltage, and the green trace is the voltage from the pot. When the input voltage is greater than the reference voltage, the MOSFET turns on, and current flows in the load. Because the frequency is relatively high (about 600Hz), we dont see any flicker from the LEDs, but the tone is audible from a motor thats PWM controlled. The PWM signal is shown in blue. The average current through the load is determined by the ratio of on-time to off-time, and when both are equal, the average current is exactly half of that which would be drawn with DC.

Figure 2 - Dimmer/Speed Controller Schematic

The circuit is shown in Figure 2. U1 is the oscillator, and generates a triangular waveform. R4 and R5 simply set a half voltage reference, so the opamps can function around a 6V centre voltage. U2A is an amplifier, and its output is a 10V peak to peak triangle wave that is used by the comparator based on U2B. This circuit compares the voltage from the pot with the triangle wave. If the input voltage is at zero, the comparators output remains low, and the MOSFET is off. This is the zero setting.

In reality, the reference triangle waveform is from a minimum of about 1.5V to a maximum of 9.5V, so there is a small section at each end of the pots rotation where nothing happens. This is normal and practical, since we want a well defined off and maximum setting. Because of this range, for lighting applications, an industry standard 0-10V DC control signal can be used to set the light level. C-BUS (as well as many other home automation systems) can provide 0-10V modules that can control the dimmer.

While a 1N4004 diode is shown for D2, this is only suitable if the unit is used as a dimmer. For motor speed control, a high-current fast recovery diode is needed, such as a HFA15TB60PBF ultra-fast HEXFRED diode. There are many possibilities for the diode, so you can use whatever is readily available that has suitable ratings. The diode should be rated for at least half the full load current of the motor, and the HFA15TB60PBF suggested is good for 15A continuous, so is fine with motors drawing up to 30A.

Construction

While its certainly possible to build the dimmer on veroboard or similar, its rather fiddly to make and mistakes are easily made. Also, be aware that because of the current the circuit can handle, you will need to use thick wires to reinforce some of the thin tracks. This is even necessary for the PCB version. Naturally, I recommend the PCB, and this is available from ESP. The board is small - 53 x 37mm, and it carries everything, including the screw terminals. The PCB is double-sided with plated-through holes, and has solder masks on both sides.

The MOSFET will need a heatsink unless you are using the dimmer for light loads only. It is necessary to insulate the MOSFET from the heatsink in most cases, since the case of the transistor is the drain (PWM output). For use at high current and possible high temperatures, the heatsink may need to be larger than expected. Although the MOSFET should normally only dissipate about 2W or so at 10A, it will dissipate a lot more if its allowed to get hot. Switching MOSFETs will cheerfully go into thermal runaway and self destruct if they have inadequate heatsinking. You may also use an IGBT (insulated gate bipolar transistor) - most should have the same pinouts, and they do not suffer from the same thermal runaway problem as MOSFETs.

As noted above, there are many different MOSFETs (or IGBTs) and fast diodes that are usable. The IRF540 MOSFET is a good choice, and being rated 27A it has a generous safety margin. There are many others that are equally suitable - in fact any switching MOSFET rated at 10A or more, and with a maximum voltage of more than 20V is quite ok.

Testing

Connect to a suitable 12V power supply. When powering up for the first time, use a 100 ohm "safety" resisor in series with the positive supply to limit the current if you have made a mistake in the wiring. The total current drain is about 2.5mA with the pot fully off, rising to 12.5mA when fully on. Most of this current is in the LED, which is also fed from the PWM supply so you can see that everything is working without having to connect a load.

Make sure that the pot is fully anti-clockwise (minimum), and apply power. You should measure no more than 0.25V across the safety resistor, rising to 1.25V with the pot at maximum. If satisfactory, remove the safety resistor and install a load. High intensity LED strip lights can draw up to ~1.5A each, and this dimmer should be able to drive up to 10 of them, depending on the capabilities of the power supply and the size of the heatsink for the MOSFET.

source: http://sound.westhost.com/project126.htm

Friday, October 17, 2014

Sub Woofer and Controller Circuit Diagram

This is a simple Sub-Woofer and Controller Circuit Diagram. Sub woofers are popular, with home theater being of the driving forces. However, a nice sub adds considerably to normal hi-fi program material, & so if it is predictable & has nice response characteristics.

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.

Completed Prototype

A fast word is warranted here, to let you decide if the speaker you have will actually work in a little sealed enclosure. The EAS principle will permit any driver to extend to twenty Hz or even lower. A lovely fast check is to stick the speaker in a box, and drive it to 100W or so at twenty Hz - you ought to see lots of cone movement, a few things will rattle, but you should not actually listen to a tone. A "bad" speaker will generate 60 Hz (third harmonic) - in the event you dont listen to anything, the speaker will work in an equalized sub.

If a tone is audible, or the speaker shows any signs of distress (such as the cone breaking up with appropriate terrible noises), then the driver cannot be used in this manner. Either discover a different driver, or use a vented enclosure.

Before you can build your own EAS box, you will require to pick an appropriate driver, using the above as a guide. Cone tour will be high at the lowest frequencies, so the speaker needs to be able to high power, lovely tour, & of reasonable size (there is no substitute for cone area for moving air at low frequencies). I am using a 380mm (15") driver, but smaller drivers (say 300mm - 12") can be used, or even a bigger number of smaller drivers. I have also had excellent results with a single 300mm driver, which has lower sensitivity (as would expect) but is perfectly adequate for normal usage.

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 box I built is made from 25mm (1") MDF (Medium Density Fiberboard), & filled with fiberglass. Apart from the fact that it is very heavy (which is a lovely thing, because it desires to walk with low frequencies), the cabinet is acoustically dead, with no resonances in the low frequencies at all ( unlike my house & furniture, dammit !). The woofer is recessed in to the baffle, & sealed with weather sealing foam. When attaching the speaker, do NOT use wood screws, or any other screw in to the MDF. I used "Tee" nuts. I have no idea what they are called elsewhere in the world, but they look like this

TEE NUT

The middle is tapped, and accepts a metal thread screw, and the small spikes mean that you must drill a hole, and hammer in the Tee nut. In case you use a screw through the hole and screwed lightly in to the Tee nut, you can hold it in place as you bash away at it, and can also see that it is straight when you are done. make sure that the finish of the screw doesnt stick out the finish, or you will seldom remove it again after the hammering! I recommend that you lock the tee nut in to place with some construction adhesive (dont get any in the threaded section) so they dont fall out while you are installing the speaker.

The EAS Controller
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.

Figure 1 - The Original EAS Filter / Controller

It turns out that the controller can be simplified, but there is no point. While the dual pot appeared like a lovely suggestion when I built my unit, it actually only changes the gain. Now, having experimented some more, this is an excellent thing, since it means that the level through the controller can be set to make positive that there is no distortion - there can be a immense amount of gain at low frequencies, & if the gain is high, distortion is assured!

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.

It is OK to substitute different op amps, but there is tiny reason to do so. Any substitution tool ought to be a FET input op amp, or DC offset may be an issue. Do not be tempted to make use of a DC coupled amp. If the you are planning to make use of is DC coupled, the input ought to be isolated with a capacitor. Pick a value to give a -3dB frequency of about 10Hz, as this will have tiny effect on the low frequency response, but will help to attenuate the subsonic frequencies.

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.

To permit lower frequencies, you can increase the 100k shelving resistors (R6 and R9) to 220k, and increase the high pass capacitors (four.7uF) with 10uF (or R4 & R7 may be increased - a maximum of four.7k is recommended). This will give a turnover frequency of around 8Hz, but expect to make use of much more power, as there will likely be significant sub-sonic energy that will generate huge cone excursions with no audible benefit.

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!

For the power supply, use the in anything else will provide +/-15V at a few Milli amps. My supply is not even regulated, & the whole method is as close to noiseless as you will listen to (or not listen to). Construction is not critical - I built mine on a piece of Overboard (perforated prototype board), & managed to fit everything (including the power supply rectifier & filter) on a piece about 100 x 40 millimeters with room to spare.

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.

Performance Of My Prototype
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.

A couple of orchestral recordings revealed traffic (or perhaps underground railway) rumble that I was unaware of before (however this was before it was set correctly, and the bass was a tad louder than needed). One time set up properly, its presence is unobtrusive - except I now have about and a half octaves of additional bottom finish.

I finally decided on a 20Hz maximum frequency (-3dB), and this is reflected in the part values shown in Figure one. The actual roll-over frequency is 16.5Hz, after which the output is attenuated at about 12dB / octave (see Figure two). Without the roll off capacitors, the gain would be 20dB at 20Hz. Unity gain frequencies are about 4Hz and 63Hz with the 20k pot(s) centered.

Figure 2 - Frequency Response of EAS Controller

awesome Australian readers may recognize the woofer brand in the picture (Figure three) of my done unit. The compact size of the box can be seen from the fact that there is tiny spacing around the speaker itself, and most of what is there is the top and sides - I used 25mm MDF, so it makes the outside of the box a bit bigger than the inside. Outside dimensions are 470W x 450H x 410D (18 1/2"W x 17 1/2"H x 16"D), which gives a capacity of 60 liters (about two.1 ftÂ³ - excluding the internal space occupied by the speaker. I think you would agree that this is a small box indeed for a 380mm loudspeaker that performs down to 15Hz.

Figure 3 - Photo of Completed EAS Cabinet

Overall, I would must say that I doubt that any conventional design would be as compact, or would have such clarity & solidarity. Being a sealed box, there is not of the "waffle" that ported designs often give, & the speaker is protected against excessive tour by the air pressure in the box itself (below the cutoff frequency, anyway).

The bottom finish in my technique is now staggering. It is rock solid, & absolutely thunders when called on. The 400W amp is over sufficient for the job, thinking about its to keep up with a biamped main technique able to high SPL (up to 120dB at my listening position). In fact a fast check indicates that 200W would have been (but . better to have it & not require it than require it & not have it).

The fact that the EAS design augments the existing speakers than taking over from them with a crossover goes a long way towards ensuring the power requirements do not get out of hand. As an added benefit, I have found that I get the same aural sensation at much lower SPLs - I can listen happily at 90dB, but it sounds much louder. I may even listen to the phone ring while listening now !

All in all, I feel it is unlikely that anything other than an isobaric enclosure could give the same performance for a box size even close to the EAS box,& even then would be limited to about 35Hz. Added to this is the unpredictable combined response of the main speakers and the sub, which is not an Problem with this design. With an EAS system, more power is necessary than a standard design, but for plenty of people, power is less costly than space.

Thursday, October 2, 2014

Digital Volume Controller Circuit

The circuit shown here is based on the switching action of transistors.
Volume of a stereo deck can be controlled with the help of a potentiometer which changes the resistance between the output of the preamplifier and input of the amplifier. This can be done with the help of decade counter, IC.4017 and some transistors.

The input is applied at collectors and the output is taken from emitters of the transistors. Depending upon the output of IC 4017, the corresponding transistor gets saturated. Output from the emitters is taken through a coupling ” capacitor to block the DC components. When pin 4 of IC 4017 ° goes high, the corresponding transistor (T2) gets saturated and the input signal is directly fed to the output through the collector resistance-:

To start with, press switch S1. The timer IC (IC 555) will start generating pulses at equal interval of time which are fed to IC2. Depending on the output of IC 4017 the transistor is selected. When desired volume reached; release the switch.

To reset the counter, switch S2 is brought to position A. The time period of the output pulses · can be set, using the formula Td: 0.693 (R1 +2VR1 + 2R32) C1 seconds.

Digital volume controller circuit diagram:

High Torque DC Motor Speed Controller Circuit Bidirectional Motor Speed Controller

The speed of DC motors is relatively simple to control.
For independently energized motors, the speed is, in principle, a linear function of the supply voltage. Motors with a permanent magnet are a sub category of independently energized motors, and they are often used in toys and models. In this circuit, the motor supply voltage is varied by means of pulse width modulation (PWM), which ensures good efficiency as well as a relatively high torque at low motor speeds. A single control voltage between 0 and +10 V enables the motor speed to be reversed and varied from nought to maximum in both directions. Astable multivibrator IC1 is set up as an 80 Hz oscillator, and determines the frequency of the PWM signal.

Current source T1 charges C3. The sawtooth , voltage across this capacitor is compared with the control voltage in IC2, which outputs the PWM signal to buffer N1-N3 or N4-N6. The darlington based motor driver is a bridge circuit capable of driving loads up to 4A, provided the run-in current stays below 6A, and sufficient cooling is provided for the power transistors Tz T5. Diodes D2-D5 afford protection against inductive surges from the motor winding. Switch S1 makes it 1 possible to reverse the motor direction instantly.

Wednesday, September 17, 2014

Simple Kitchen Exhaustion Fan Controller Circuit

Exhaustion fan is a very important element in kitchens. Here may be a easy circuit to manage kitchen fans by monitoring the ambient temperature. its engineered round the renowned precision integrated temperature sensor chip LM35 (IC1). remainder of the circuit may be a non-traditional electromagnetic relay driver wired round the fashionable LED driver LM3914 (IC2). User will switch 3 presetted temperature levels employing a jumper/slide switch (JP1), that determines the warmth level to activate the relay and hence the electrical exhaustion fan wired through the relay contacts. It works off 12V DC power offer.

Kitchen Exhaustion Fan Controller Circuit Schematic

Only one adjustment is needed during this kitchen Exhaustion fan controller circuit. when construction, set jumper purpose in its 1st position, ie base terminal of T1 is connected to pin thirteen of IC2 and alter the preset P1 fastidiously in order that relay RL1 is energised when ambient temperature level reaches close to 29oC. but this is often not terribly vital as youll choose any threshold level by connecting the jumper points to alternative unused output pins of IC2 (here solely three outputs are used).

Sunday, September 14, 2014

Automatic Water Pump Controller Wiring diagram Schematic

Simple Automatic Water Pump Controller Circuit Diagram is a series of functions to control the Automatic Water Pump Controller Circuit in a reservoir or water storage. As the water level sensor made with a metal plate mounted on the reservoir or water tank, with a sensor in the short to create the top level and a detection sensor for detecting long again made the lower level and ground lines connected to the bottom of reservoirs or reservoir.

The series of automatic water pump controller is designed with 2 inputs NOR by 4 pieces and relay that is activated by the transistor. Automatic water pump schema requires +12 VDC voltage source and can be used to control the water pump is connected to AC power . Here is the complete series of pictures.

Automatic Water Pump Controller Circuit Diagram

working principle series of automatic water pump controller above is. At the time the water level is below both sensors, the output IC1C (pin 10) will be LOW, Kemudin when the water began to touch the lower level sensor, the output IC1C (pin10) remains LOW until the water touches the sensor level above, then the output IC1C (pin 10) going HIGH and active relay through Q1 and turn on the water pump to meguras reservoir.

At the muli down and water level sensors for water untouched MKA IC1C output (pin 10) remains HIGH until the new water untouched semuasensor IC1C output (pin 10) LOW and water pump died. The series of automatic water pump controller is equipped with SW1 which serves to reverse the logic of drains (the output of IC1C) and the concept of water supplied (output dri IC1D).

When SW1 is connected to IC1D the water pump will turn on when the water does not touch all the sensors and will die when all the sensors tesentuh water. Automatic water pump controller can be used to fill or drain the water according to which mode is selected via SW1.

List Component Automatic Water Pump Controller

R1 = 15K

R2 = 15K

R3 = 10K

R4 = 1K

D1 = LED

D2 = 1N4148

Q1 = BC337

IC1 = 4001

SW = SPDT Switches

Relay RL1 = 12V

Saturday, September 6, 2014

Automatic fan controller circuit

This schema will turn on/off 12V DC fan or CPU fan when temperature above normal temperature.You can set turn on temperature by adjust VR1. This schema use an NTC (Negative temperature coefficient)which is a thermistor is one in which the zero-power resistance decreases with an increase in temperature. So If temperature increate the voltage at pin 3 on LM311 will decreated .The resistance of NTC is about 10K at 25c.

VR1 should be multi-turn potentiometer type such 10K/25 turn