Serial Port Holiday Light Flasher

In this post I will show you how to flash Christmas lights by the serial port. Now you can with Holiday232. This serial port can switch between 4 different lights by using 2 SPDT relays and both RTS and DTR of the relay. As you may be wondering when looking at the schematic why I’m […]

$32 dollar isolation transformer

Here’s a simple easy to build Isolation Transformer that you can buy from All Electronics. Here’s what you need: 1x 120VAC Output transformer 1x outlet connector 1x power cord You can add a 1/2A fuse that goes on the output of the transformer

Things you can do with Soundcards

There are a couple things a soundcard could come in handy for electricians. Dual channel oscilloscope and RCL meter/ The first circuit shows you a design for oscilloscope: That circuit gives an impedance <500K on CH1 and CH2. R1 and R2 adjust the voltage range. R3 and R4 is for current limiting resistors for the […]

DIY Battery Load Tester

In this blog post I will go over steps of testing a battery. This method is not just for golf cart batteries, it works with most batteries(although the resistance might be different) that give a good wattage without going over the wattage rating of the resistor. Another thing I should tell you is don’t forget […]

LED Tester

Here’s a simple LED tester that allows you to test LEDs, see how bright they are and let’s you see the forward voltage drop used to figure out the current limiting resistor. We use a 100mA LM317 current regulator. By doing this you can see how the LED reacts to different currents. In this circuit […]

DIY Holiday Lights

In this blog I will show you how to build holiday lights. This idea came from Penny who wanted to get green lights and come to find out they are not in store.You can take LEDs and wire them in parallel with a current limiting resistor for each one. Or to speed up soldering just […]

TV coax oscilloscope probe

In this blog post I will show you how to build a x1 probe and a x10 probe. You will need resistors, a pen(prefer one with the tip can come off),6ft or less of TV coax, paper clip,one alligator clip, 1 Meg impedance oscilloscope and a f jack to BNC adapter. You will want to […]

Passive Ethernet Tap

A Ethernet tap allows you to monitor Ethernet communications going through the tap. The circuit uses no power and that is why its called passive. Can be made by cutting Ethernet cords and/or soldering or crimping. This method will make the maximum Ethernet speed 100Mbps, even if its a gigabit Ethernet. Also you could use […]

Sawtooth generator for TV oscilloscope

Here’s what I come up with for sawtooth signal for the scope. I took the ramp generator circuit from It uses 3/4 Op Amps from the LM324 chip. I tested the circuit from and it works in multisim. S1 and R8 controls the frequency. R6 controls the amplitude of the sawtooth voltage. When […]