Electronics Infoline Web

Simple high-pass filter to cut off disturbing signals

http://www.hard-core-dx.com/nordicdx/antenna/special/highpass.html

Simple laser-diode controller

http://www.edn.com/article/CA243224.html

Simple logic probe uses bicolor LED

can measure high, low, and high-impedance logic states, in addition to indicating switching logic states

http://www.edn.com/archives/1998/031398/06di.htm

Simple MIDI tester

This converts the midi signals to visible light pulses. Just the circuit and plug it to the MIDI output of your computer. When computer sends any midi data out, you see the LED flashing.

http://www.tkk.fi/Misc/Electronics/circuits/miditest.html

Simple monovibrator uses three PLD pins

if you can afford just three spare PLD pins, this circuit is an alternative to using yet another 555

http://www.edn.com/archives/1995/092895/20di6.htm

Simple Polarity Tester

check the polarity of any source up to 12V DC or AC

http://www.aaroncake.net/circuits/polarity.htm

Simple Power Meter

http://www.qsl.net/g3pto/pomtr.html

Simple printer emulator adapter

This circuit is a simple adapter for PC parallel port to think that there is a printer connected to computer. This adapter is useful for testing printing speed with different software and as a part of your own designs.

http://www.tkk.fi/Misc/Electronics/circuits/nullprint.html