This crystal oscillator is indicated for the calibration of IF steps of common radio receivers. The transistor admits equivalent as 2N2222 or BF494. The circuit is from an old American publication.
This one-digit TTL modulus for 7-segment display can be parto f digital projects. Many of them can be...
Radio Electronics magazine published in a 90's issue this simple alarm that can use any general...
The basic application of a 4017 as a sequencer [10 steps] is shown here. In this same part, you...