This interesting digital counter with relays with complementary outputs was found in the Radio Electronics magazine of October 1961. The supply voltage is in accordance with the relays used.
This small FM transmitter, with a few tens of meters in range, is powered by a 9 V battery. The...
This filter was obtained from the Texas Instruments Linear Circuits Applications. It makes use of...
Figure 1 shows a simple audio oscillator driven by the SCR When the sensor is closed. The circuit...