This circuit was found in a Popular Electronics from the 90's. The CMOS integrated circuit used is not very common nowadays. The range depends on the infrared LEDs. R7 can be changed.
In the figure we have an amplifier from the 50s using the CK721. The circuit has a voltage gain of 5...
This circuit came out in a publication called Electronics Handbook of 1993. Q1 can be a 2N2222 or even...
The integrated circuit used in this small transmitter is not very common today. The coil has its...