Institute Newton C. Braga

Circuit Bench

Single Crystal Filter (CB6542E)
High selectivity filters can be obtained by combining same frequency crystals in series as shown...
LM390 Intercom (CB25310E)
This two-channel wired intercom was found in the April 1990 issue of Radio Electronics magazine....
Electronic Compass For Blind (CB4551E)
The basic idea of this circuit is to convert the indication of a magnetic sensor to an audio tone...