This digital voltmeter is ideal to use for measuring the output voltage of your DC power supply. It includes a 3.5-digit LED display with a negative voltage indicator. It measures DC voltages from 0 to 199.9V with a resolution of 0.1V. The voltmeter is based on single ICL7107 chip and may be fitted on a small 3cm x 7cm printed circuit board. The circuit should be supplied with a 5V voltage supply and consumes only around 25mA.
Posted on Wednesday, April 2, 2008 • Category: FM Transmitters
Be "On Air" with your own radio station! BA1404 based transmitter is an exciting product that will broadcast a high quality stereo signal in the 88 – 108MHz FM band. It can be connected to any type of stereo audio source such as personal computer, CD player, Walkman, television, tape deck or stereo system to transmit stereo sound with excellent clarity throughout your home, office, yard or camp ground.
Posted on Wednesday, April 2, 2008 • Category: Power Supplies
This is a LM338 based power supply which is not complicated and easy to build. I am using the supply for a long time, have no problem yet. Only current adjust is missing but I overcome this situation by using an LCD panel ampermeter. There is no PCB for the circuit. I took a 3x16 copper plate and strip the unused areas by a knife. If you want you can use analog meters instead of LCD panels.
Posted on Wednesday, April 2, 2008 • Category: Remote Control
How many times you needed some remote control to handle some electric device ? many times. There are lot of remote controls like infrared, RF, SMS (like my other circuit) and more. The basic small-range remote controls are 2, Infrared and RF (Radio Frequency). One of the weaks of Infrared is that the signal can not pass the walls. So, if you want to control your garage door, the only way is to use some RF remote control. The circuit (transmitter and receiver) use few components and ordinary (I love few component circuits) . Its easy to build it because you don't have to tune-up any coil or variable capacitor. The RF modules are fix to work in 418MHz area.
Posted on Wednesday, April 2, 2008 • Category: Headphone Amplifiers
This is a Chu Moy headphone amp I made. I got the PCB design from Guzzler from Head-Fi and the original design is very popular and is here. I changed Guzzler's layout so I could use a Taiwan Alpha pot on the PCB. These pots a high quality (some say better than ALPS blue velvet) and are available from Jaycar. You can see the thread here. I also made a DIY Brown dog adapter so I could use two OPA627 single opamps in a dual opamp socket.
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