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Monday, February 21, 2011

Simple Positive (+) to Negative (-) Voltage Inverter Circuit

This is a simple circuit that can be used to convert the positive input voltage become negative voltage. Here’s the figure of the circuit;

Component list:

Part    Total Qty.    Description          
R1    1    24K 1/4 Watt Resistor          
R2    1    56K 1/4 Watt Resistor          
C1    1    3300pF 25V Ceramic Capacitor          
C2    1    47uF 25V Electrolytic Capacitor          
C3    1    10uF 25V Electrolytic Capacitor          
D1, D2    2    1N4148 Silicon Diode          
U1    1    555 Timer          
MISC    1    Wire, Board         

In this circuit, V+ can be anywhere from 4 to 16V. -V is one volt less than V+. So, for -12V output, use +13V input. The maximum current output of the circuit is about 280mA, more than enough for a few op amps. For better regulation, a 79LOxx series regulator can be used. A zener diode may also be used to regulate the output voltage.

Simple Galvanometer Circuit

This circuit is design for galvanometer circuit. According to, a galvanometer is an analog electromechanical transducer to be used for detecting and measuring electric current (ammeter). In this circuit design, the voltage across Rm and Rv is the same because they are in parallel. The resistor Rv is a variable resistor. Here’s the figure of the circuit;

Monday, February 7, 2011

Simple R/C Circuit

Here’s a design circuit for a very easy and efficient receiver for actuating garage doors, starter motors, alarms, warning systems and numerous some other possibilities. This is the figure of the circuit;

In this circuit specifies a whip or wire antenna which just indicates a solid piece of wire 6-12 inches long (15-30cm). The antenna coil is experiments, however you can start with ten to 12 turns of #22 (0.7mm) magnet wire, and 5/16" (8mm) coil diameter. Antenna wire is soldered at 1/2 turn of the coil and the gate of the BRY35 is soldered about halfway the coil. This circuit will transmit as much as 100-feet with the above specs @ 30uA. The relay coil is specify as much as 200 ohm but that's just the one I had in stock. Any low-ohm relay, even at 9V or so, ought to accomplish the task. And one remaining note, do not be expecting too a lot from this circuit. The "Very Easy R/C Circuit" is simply that; Easy!

The BRY35 is really an classic semiconductor produced by Philips. A great replacement would be the EC103D1, also produced by Philips (see pin-out picture for this device). NTE Semiconductors gives an alternative of NTE5405, but I have not attempted it. I think, a NTE5400 (30V) or NTE5401 (60V) will function just also. The NTE5405 is a bit overkill at 400V.

Simple LED Flasher Circuit Using LM3909

This is a very -very easy and simple LED flasher circuit with only needs three components that are: a flasher IC, a LED and an electrolytic capacitor. Here’s the figure of the circuit;

Component list:
LED1_________Red LED

Infrared Modulation Identifier Circuit

This is a design circuit for Infrared Modulation Identifier using remote control. Here’s the figure of the circuit;

In this circuit illustrates how the modulated carrier of infrared is measured by displaying the waveform on a frequency counter after the signal received is amplified.