Wiring circuit

Showing posts with label meter. Show all posts

Thursday, October 30, 2014

LED Audio Level Meter Circuit

This circuit uses two quad op-amps to form an eight LED audio level meter. The op-amp used in this particular circuit is the LM324. It is a popular IC and should be available from many parts stores.

LED audio level meter schematic

The 1K resistors in the circuit are essential so that the LEDs turn on at different audio levels. There is no reason why you cant change these resistors, although anything above 5K may cause some of the LEDs to never switch on. This circuit is easily expandable with more op-amps, and is not limited to use with the LM324. Pretty much any op-amp will work as long as you look up the pinouts and make sure everything is properly connected.

The 33K resistor on the schematic is to keep the signal input to the circuit at a low level. It is unlikely you will find a 33K resistor, so the closest you can get should do. The value of this resistor may need to be changed, so it is best you breadboard this circuit before actually constructing it on PCB. The circuit in its current form will accept line level inputs from sources such as the aux out on a Hi-Fi, all though could be easily modified to accept speaker inputs.

The audio + is connected to the main positive rail, while the audio - is used for signal input. The 50k pot can be used to vary the sensitivity of the circuit.

Saturday, September 13, 2014

Remote Field Strength Meter Wiring diagram Schematic

Remote Field Strength Meter Circuit Diagram. This field strength meter consists of a tuned crystal detector producing a dc output voltage from a transmitted signal. The dc voltage is used to shift the frequency of a transmitter of 100-mW power operating at 1650 kHz. The frequency shift is proportional to the received field strength. This unit has a range of several hundred feet and is operated under FCC part 15 rules (100-mW max power into a 2-m-iong antenna between 510 and 1705 kHz).

Remote Field Strength Meter Circuit Diagram

Wednesday, September 10, 2014

LED Audio Level Meter Circuit

This circuit uses two quad op-amps to form an eight LED audio level meter. The op-amp used in this particular circuit is the LM324. It is a popular IC and should be available from many parts stores.

LED audio level meter schematic

The audio + is connected to the main positive rail, while the audio - is used for signal input. The 50k pot can be used to vary the sensitivity of the circuit.

Friday, September 5, 2014

LED Power Meter

LED power Meter circuit is a simple RF detector using diodes to charge a capacitor. The voltage developed across the capacitor is indicated by a multimeter set to a low voltage range. The circuit is soldered together without the need for a PC board, as can be seen in the diagram below and paper clips are used for the positive and negative terminals of the multimeter.

The level power output of an FM transmitter is indicated by the illumination of a LED and the voltage reading on the multimeter gives a further indication of the output.

A digital multimeter may be used but the presence of RF may produce a false reading. Likewise, the radiated energy may upset some analogue meters and you may get full scale deflection on the 15v range as well as the 250v range! But the LED wont lie. It will accurately indicate the RF and you can see the change in brightness as you adjust the coils in the output stage. Some of the cheapest and simplest multimeters will give the best results as they have a low sensitivity and the radiated RF energy will not induce a reading. Even a damaged multimeter can be used, provided the 10v or 15v DC scale is operating.

The reading is not calibrated and does not represent milliwatts output. It is only a visual indication.

We have designed over 10 FM transmitters for inclusion in the pages of this e-magazine and each one has different features and characteristics. Some are designed for 3v operation, some are for 9v operation, some are stable for hand-held situations and others are designed for high output. The illumination of the LED will range from barely visible to very bright.

LED Power Meter Parts

1 - 470R

1 - 100p ceramic

1 - 100n ceramic

2 - 1N 4148 diodes

1 - 5mm Red LED

1 - 2in (5cm) hook-up wire

2 - paper clips

No PC board required

Wednesday, September 3, 2014

VU Meter 5 with UAA180

This schema of measurement of level uses the UAA180 of SIEMENS and a schema of rectification of precision, round the IC2B. The calibration has become in steps 3db from the one Led in the other, ensuring, a very good rate of precision, in the measurement of entering acoustic signals. The Led can be square, thus when they are placed the one by in the other, they give the picture of bar, without space. VU Meter 5 with UAA180 Circuit diagram: Parts List: R1= 47Kohm
R2= 1Mohm
R3= 33Kohm
R4= 10Kohm
R5= 220ohm
R6-9=390ohm
R7=2.2K ohm
R8-10=330Kohm
R11=180Kohm
C1= 47uF 25V
C2-4=47nF 100V
C3=2.2uF 25V
D1....8= LED GREEN
D9-10= LED YELLOW
D11-12= LED RED
D13....17= 1N4148
IC1= UAA180
IC2= TL072

[Link]

Monday, August 25, 2014

Field strength meter

Here is a handy field strength meter that can be used to check the strength of AM radio signals.The schema is a very useful for those who assemble radio transmitters(especially in the tuning of the final stage for maximum range).

The schema is essentially some sort of a AM receiver it self. The capacitor C3 and inductor L1 forms a tuned schema to receive a particular frequency(the frequency of your transmitter).The diode D1 detects the signal and applies to the base of transistor Q1 (MPSA 18).The collector current of the Q1 will be proportional to the strength of this signal and will be shown in the meter M1.In result the meter reading will be a measure of the strength of the signal (of the tuned frequency) falling on the antenna.

Notes.

* The C3 must be varied to tune in to the frequency of your transmitter.For that,keep the antenna of meter schema close to the antenna of your transmitter and adjust C3 to get a maximum reading on meter M1.
* Now the meter is tuned to your frequency.
* In order to tune your transmitter for a maximum range, place the meter schema some place near to the transmitter and adjust the transmitters tuning elements.Maximum range setting will at the point where the meter shows full deflection.
* Power the schema using a 9v battery.
* The antenna can be a 15 cm long Copper wire.
* The transistor Q1 can be any high gain NPN RF transistor.
* Switch S1 is used as a power switch.Keep this switch OFF when schema is not in use to save battery life