LED Voltage Level Indicator

 Discrete-Circuits, LED-Circuits  No Responses »
Jul 302005
 
LED 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 Read More …

 Posted by admin at 9:05 AM

Mains Voltage monitor using LM3914

 LED-Circuits, Mains-Power, Test-Measurement  No Responses »
May 022005
 
Mains Voltage monitor using LM3914

This Circuit helps in the monitoring of mains supply voltage. It does not use a isolation step down transformer. This has to be constructed only by skilled people with knowledge of safety requirements. C1 limits the current and drops most of the voltage. The zener regulated supply is for the chip. C2 can be raised to 220uF or more if required. The bar mode display may consume more power. R2-R3-R5-R6 form a voltage divider to get a sample of the input voltage, D11-C3 get the DC value. Adjust R5 preset with a log Plastic tweaker to get the 5th led Read More …

 Posted by admin at 8:05 PM

Simple Mains Voltage monitor

 LED-Circuits, Mains-Power, Opamp-Circuits  No Responses »
May 022005
 
Simple Mains Voltage monitor

This Circuit helps in the monitoring of mains supply voltage. It does not use a isolation step down transformer. This has to be constructed only by skilled people with knowledge of safety requirements. C1 0.47uF can be brought down to 0.22uF for low LED currents, use high efficiency ultra bright LEDs.C1 should be 440V AC or 630V DC plastic axial yellow, polyester, polycarbonate, polypropylene, metalized film. R3-R6-R9-R14-R18 resistor divider determines the LED turn on or threshold switch points, 10M for hysteresis. Adjust R16 preset with a log Plastic tweaker to get the led D2 to turn on when input voltage Read More …

 Posted by admin at 8:04 PM

Mains Current Indicator with a LED

 Discrete-Circuits, LED-Circuits, Mains-Power  No Responses »
Nov 302004
 
Mains Current Indicator with a LED

This is a mains 230V AC load current indicator and is a LIVE CIRCUIT, so take care. The Resistors have to be a fusible ceramic wire wound. This circuit has been drawn from my memory and i have not tried it out again, just see if it is ok and then try. You should use the fuse of 1A a slow blow if you want but it is very important. You can design the shunt R3 and Fuse rating as required by your load. Note that this circuit is to be put in series with the load like an ammeter. Read More …

 Posted by admin at 2:47 AM

Mains Voltage Indicator with a LED

 Discrete-Circuits, LED-Circuits, Mains-Power  No Responses »
Nov 302004
 
Mains Voltage Indicator with a LED

This is a mains 230V AC voltage indicator and is a LIVE CIRCUIT, so take care. The Resistor has to be a fusible ceramic wire wound and the capacitor 630V AC or higher capacity. This circuit has been drawn from my memory and i have not tried it out again, just see if it is ok and then try. You should use the fuse of 100mA a slow blow if you want but it is very important. This circuit has to be enclosed in a plastic sealed enclosure to avoid contact.

 Posted by admin at 2:46 AM

Battery Level Indicator

 LED-Circuits, Opamp-Circuits, Power-Supplies  No Responses »
Oct 312004
 
Battery Level Indicator

This circuit uses a LM339 pdf, a quad comparator. LM339 pdf can work on single or dual supplies, it has a open collector output that can drive 15mA, low power consumption. The circuit is an untested design but it should work. I did it as many searches were made in my webpages with these keywords. There are many better circuits in the various circuit archives i have linked on the front page, you just have to look around. When you measure the open circuit voltage of a battery with a high impedance DMM (10M), the value may be a bit Read More …

 Posted by admin at 1:18 AM  Tagged with:

Running Lights with CD4017

 555-Circuits, Digital-Circuits, LED-Circuits  No Responses »
Oct 292004
 
Running Lights with CD4017

The 555 Astable generates a clock for this circuit, an oscillator giving a square wave output at pin 3 which is counted by 4017 to give a running lights effect. The decade counter-divider CD4017 has 10 outputs, for every low to high transition at the clock input, rising edge, the counter advances one LED. After going one full circle the the first LED lights again and it goes on. You can vary the value of R2 100K Linear potentiometer to make LEDs run fast or slow. The frequency of oscillation of astable 555 is given as f = 1.44 / Read More …

 Posted by admin at 11:27 AM
 Older Entries  Newer Entries
© 2011 delabs Schematics - Electronic Circuit Suffusion theme by Sayontan Sinha