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Posts Tagged ‘Volt meter’

Voltage Level Indicator

This circuit is derived from a Siemens Application Note 1974. This circuit uses common components of today. The circuit is here as it is of high educational value. I have not tested it. You can ‘simulate and test’ or ‘wire it up and try’ and let me know how it worked. The Circuit is also a simple analog to digital converter. You can use optos in place of LEDs.

T1 and T2 make a differential amplifier. T3, T4 and T5 driving the LEDs are comparators. Now to learn more on how they work you have to study circuits at 4QD-TEC and search Educypedia for more. Some pspice ideas here and at 101Science.com.

Read More Source :http://schematics.blogspot.com/2005/07/voltage-level-indicator.html
Thank you.

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High Voltage Protector for Meters by CA3130

Normally, in a digital voltmeter, high input impedance of the preamplifier stage is protected against very high voltages by two diodes. One of them is connected to the positive terminal and the other one is connected to the negative terminal of the power supply. Practically this kind of protection is very sufficient. But the diodes that are used for this process must have very low leakage current values. The main problem is that kind of diodes are expensive and it is sometimes hard to provide them. On the other hand electronic hobbyists commonly choose general purpose diodes like 1N4148. But this situation causes to occur some millivolts on 1M input impedance. Today, it is usually very important to measure the values with high accuracy so this extra voltages will affect our experimental results.

Read More Source:http://www.circuit-projects.com/high-voltage-protector-for-meters-by-ca3130.html
Thank you.

Other circuits
CA3130 op-amp circuits
Volt Meter circuit
Voltage indicator
Voltage monitor circuit
Voltmeter circuit
Level voltage indicator
single digit voltmeter by IC 4028 LM311
3 Digits Digital Volt Meter with PIC16F676
0 – 5V PIC Voltmeter by IC PIC16F876
ICL7107 – ICL7106 – DIGITAL VOLTMETER

AC Current Monitor by LM358,LM324

Senses high current-flow into power cables
No wire-cutting, three versions available

The basic circuit is shown top left in the drawing and must be used in all three versions. IC1 acts as a differential amplifier having a gain of 220. The small AC voltage picked-up by L1 is therefore amplified to a value capable of driving the LED D1.
The second version is drawn bottom left, must be connected to the basic circuit and uses a dual op-amp: therefore IC1 will be labeled IC1A and its pin layout varies slightly. IC1B acts as a voltage comparator and its threshold voltage can be precisely set by means of trimmer R6. Q1 is the Relay driver and D2 illuminates when the Relay is on. You can use the Relay contacts to drive an alarm or a lamp when the AC load exceeds a pre-set value, e.g. 2KW.
The third version is shown to the right of the drawing, must be connected to the basic circuit and uses a quad op-amp, therefore IC1 will be labeled IC1A and its pin layout varies slightly. IC1B, C and D are wired as comparators. They switch on and off the LEDs, referring to voltages at their non-inverting inputs set by the voltage divider resistor chain R11-R14.
Parts:
R1,R2,R8____________1K 1/4W Resistors
R3,R4_____________220K 1/4W Resistors
R5________________100R 1/4W Resistor (See Notes)
R6_________________10K 1/2W Trimmer Cermet
R7,R10______________1M 1/4W Resistors
R9_________________22K 1/2W Resistor
R11 to R17__________1K 1/4W Resistors
C1,C3_____________100µF 25V Electrolytic Capacitors
C2,C4_______________1µF 63V Electrolytic Capacitors
D1________________5mm. Red LED
D3,D4___________1N4002 100V 1A Diodes
D2,D5,D6,D7_______LEDs (Any color and size)
Q1_______________BC327 45V 800mA PNP Transistor
IC1______________TL061 Low current BIFET Op-Amp (First version)
IC1______________LM358 Low Power Dual Op-amp (Second version)
IC1______________LM324 Low Power Quad Op-amp (Third version)
L1________________10mH miniature Inductor (See Notes)
RL1______________Relay with SPDT 2A @ 220V switch
Coil Voltage 12V. Coil resistance 200-300 Ohm
J1_______________Two ways output socket

Please read more at the original source: http://www.redcircuits.com//Page62.htm
Thank you.

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