It's a very simple circuit, for the follow-up of baby. It can however be also used for other use, as intercom etc. In the place of M1 we can we use a simple electret mic... [more]
The circuit accosted in those who they want a Vumeter that will be connected in the exit of power amplifier. [more]
Three Tube PHONO (RIAA) Preamplifiers with ECC83 [more]
A very good circuit of pre-preamplifier, for amplification of signals from heads of Moving Coil. It uses the two departments of tube ECC88, association parallel, for reduction of produced noise. [more]
It is a simple circuit of protection of telephone line from hypertensions. Placed in line and before the telephone appliance. [more]
It ιs a simple circuit for the noise reject that exists in the telephone line in ADSL connections. It works in PSTN and ISDN lines, and is placed in line and before the telephone appliance. [more]
It is a relatively simple circuit, with which we can have optical and sound clue, when we have telephone ring in the line of telephone. The calls in the line, are changed in pulses of... [more]