Heres a simple circuit that takes a audio signal(from ham radios,computers or cd players) and converts them into a telephone signal. It powers the phone line with 22vdc(It doesn’t have to be 22vdc, different voltage means different resistor is needed). The phones can run as high as 48v. If you use cordless phones the converter …
Tag Archives: diy
Capacitance substitution board
In this blog I will show you how to make a dip switches capacitor substitution board. Its very simple since capacitors add up in parallel. So if you look at the schematic you will get an idea.
Simple doorbell/alarm
This is probably the simplest doorbell or alarm circuit that is out there. The buzzer will not be constantly on since the buzzer gets switched on by a capacitor. The circuit draws hardly anything when off as you will see in the graph below. As the capacitor gets charged its current lowers down a lot. …
Arduino Video poker for the TV
Here is a project I have been working on. It hooks up to the tv and allows you to play 5 different types of video poker games. The game is in black and white and some of the suits look funny. The pinouts can be found in README.MD file. Youtube videos
Capacitor powered LED flashlight
Long time ago QVC sold a shakeable Flashlight that had no batteries just a shakeable generator and a super capacitor. This flashlight uses a 5vdc 1.5a wall wart to charge the capacitors. To figure out how long it will take to charge the flashlight you use this equation $$T=5R_{currentlimit}C$$ And for total discharge time $$T=5R_{LED}C$$ …
Yet another TV oscilloscope
In this blog post a crt TV a part and turn it into a oscilloscope. I am going to try to use a TL082 op amp to buffer and amplify the signal. It uses the deflection yoke to draw the picture on the tube. More pictures and videos will be posted here when it is …
Simplest analog computer
In this post I will show you how to make a analog computer using just resistors, switches and a 100 micro ammeter. Here’s the schematic of it: You can see the idea on how this analog computer works, it uses ohms law to get current from resistors in the circuits. Each current is limited in …
Solder Iron Foot Switch
This switch is a must for people who solder alot. It prevents the iron from overheating. Its very simple and is very cheap. Some irons like mine can heat back up fast after they have not been cooled down alot. You will need the following parts and tools: 1 foot pedal switch SPST 1 duplex …
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 …
