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Flashing Mains Neon Lamp

Here is a Neon Flasher circuit (untested) for a user request at Elex Qun. This can be built into a s...
 

Voltage Doubler

This is a Simple Voltage Doubler to boost 3V battery voltage to power some low-power 5V circuits. In...
 

FET Current Source

This is a constant current source using a FET. This is the most simple replacement to series resisto...
 

Constant Current Source LED Drive

This is a Constant Current Source LED Driver, When the LED driver Upper-NPN is driven by a voltage t...
 

Voltage Level Indicator

This circuit is derived from a Siemens Application Note 1974. ...
 

RS232 with Opto-Isolation

I had to once interface an high voltage circuit to PC, The uC had to communicate thru RS232--Comm po...
 

Relay Driver

The above is a standard way of driving Small Power Relays from Control Signals generated by Logic or...
 

Simple High speed data switch

This circuit is a small representation of a very low cost printer sharer i made very long ago. This ...
 

Edison Bulb Life Extender

The Edsion Filament lamp may be less popular, but it is the most cost-effective light even today.
 

Passive volume control

Volume control circuit for speaker 4 ohm or 8 ohm located in the another room far away. by using onl...
 

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 ...
 

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 h...
 

Isolated dual power supply

diode should be fast recovery type, for less than 100mA use 1N4148. transformer, pri-20-20, sec-60-6...
 

Sound to light converter

this was made by me when i was a kid, it was even published in a magazine, i think it will work, it ...
 

Dimmer or power control

you can use it with a bulb to vary brightness of bulb, this is a live circuit it can give a shock, e...
 

Telephone status indicator

this will monitor telephone status without loading the telephone line, this way if you have two phon...
 

Water operated relay

this was done in my early days, i have upgraded it, it ought to work, reduce the number of transisto...
 

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