This circuit is from a 1975 Miniwatts magazine, therefore using Philips components from that time, now difficult to find. The circuit directly controls a heating element via a Triac.
The frequency depends on the coil and is not found in the original documentation but should be...
This is a device for those who need to show that they know how to use digital electronics but have...
Using an operational amplifier with FET, this circuit from a 1977 publication can generate...