usb e kits presents
led volt meter
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fuctionality
A very useful votmeter with indicator leds witout the need of power supply! It has 5 indicators for 5 voltage levels (5,9,12,24,30 volt dc)
The kit is based on a quad opamp LM324.
All the needed power is directly from the voltage you measure.
The first led turns on when the measured voltage reaches 5V.
The other four leds are connected to the for outputs of the opamps.
With the help of a voltage divider we can reduce the measured voltage from 0-30 volt to 0-3 volt.
This new voltage is driven to the non inverting inputs of the opamp.
The voltage reference for the inverting inputs is taken from a voltage divider again.
Each opamp operates as a comparator that compares the tow inputs.
If the voltage level comes above the reference voltage ,
the output of the opamp goes high and drives the led that is connected to it.
When the measured voltage reaches 30 volts all the leds are turned on!
Led voltmeter schematic
part list
Reference Type Value
C1 Ceramic Capacitor 330nF C2 Ceramic Capacitor 100nF C3 Electrolytic Capacitor 22u D1 3mm difussed led Red D2 3mm difussed led Red D3 3mm difussed led Red D4 3mm difussed led Red D5 Diode 1N4148 D6 Diode 1N4148 D7 3mm difussed led Red D8 Diode 1N4148 R1 Resistor 1/4 watt 100k R2 Resistor 1/4 watt 10k R3-R6 Resistor 1/4 watt 1k R7 Resistor 1/4 watt 82k R8 Resistor 1/4 watt 22k R9 Resistor 1/4 watt 47k R10 Resistor 1/4 watt 10k R11 Resistor 1/4 watt 33k R12 Resistor 1/4 watt 1.2k R13 Resistor 1/4 watt 1k U1 QUAD Op. Amplifier LM324 U2 Voltage Regulator 7805 J1 Terminal Block 2 pin |
construction help guide
resistor color code definition
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downloads
| led_voltometer_datasheet.pdf |
watch the presentation of the kit
Led Voltometer 3,6,12,24,30 vdc levels indicators
A very useful voltometer based on the lm324 quad amplifier. Every opamp is used as a comparator at the interested voltages. So if you have a power supply and every time you have to measure the output with a multimeter do this project and you are ready to display the interest levels of the voltage.
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Led voltmeter preview
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