## 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 […]

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 learningaboutelectronics.com It uses 3/4 Op Amps from the LM324 chip. I tested the circuit from learningaboutcelectronics.com and it works in multisim. S1 and R8 controls the frequency. R6 controls the amplitude of the sawtooth voltage. When […]

## 3.8V Li-on battery charger

In this blog post I will show you an easy project that can charge Li-on batteries that have the built-in protection circuit. All you need is a 1A or higher rectifier diode, 1 amp linear adjustable voltage regulator(such as LM317), 240 and 680 ohm resistor(any wattage) and a 100 ohm trimmer(For adjusting the charging voltage).

## DIY Music controlled pumpkin

Here’s a simple and easy Halloween project. It is based off of a single ended transistor audio amplifier. The transistor amplifies the audio voltage to one that can light up an LED. The volume should be turned up all the way to get best performance. Since audio singles are hardly any strong. If you want […]

This is a simple yet effective resistor decade box. The resistors are connected in parallel with the SPDT/SPST switches. The resistance is the sum of all switches opened(NOT CLOSED!). When resistors are in series the resistances add up. $$Rt=R1+R2+R3$$ And when they are in parallel the total resistance decreases: $$Rt=\frac{1}{\frac{1}{R1}+\frac{1}{R2}+\frac{1}{R3}}$$ Rt is the total resistance […]