This electronic Morse Key for telegraph message transmission was found in an American 1980s amateur radio documentation. The circuit uses TTL technology and must be powered by a 5V voltage.
The original document is from Philips, but now available from NXP (www.nxp.com) which is the...
In the figure we show how to implement a voltage-controlled oscillator. The circuit is from Texas...
Three LM158, LM258, LM358, or LM2904 operational amplifiers are used in this instrumentation amplifier....