With an 18 V input, this regulator was found in Philips documentation from the 60's. The transistors are from that time. The power transistor must have a heatsink.
This circuit is from a 1995 publication. The components are all common and the number of LEDs may...
Using a new Maxim integrated circuit (www.maxim-ic.com) the amplifier shown in the figure can be...
We found this circuit in a Motorola publication from the 70s. The circuit can be implemented with...