Ron, across the load, the scope sees some AC. It is not a sine wave. It is circa 5 mVpp, and looks like it changes alternates quickly, but sort of evenly.M
I installed a diode between the 7805 and base. The AC wave is gone. However, something else happens. When I ground the load, a noise appears, but after 4-5 seconds it dies down! What do you think?M
The wires of your breadboard are too long and have series inductance. If you used a small compact pcb like all REAL circuits then maybe adding a 0.1uF ceramic disc capacitor with short leads to the output and ground (like in the datasheet) will kill the oscillation.
The wires of your breadboard are too long and have series inductance. If you used a small compact pcb like all REAL circuits then maybe adding a 0.1uF ceramic disc capacitor with short leads to the output and ground (like in the datasheet) will kill the oscillation.
Before I connect the lead to the collector of the npn transistor, i only get 5V from 7805 via the base. Once i connect the main current to the collector, I get this AC current.
If you don't post the correct schematic, then we can't really help, the datasheets clearly show you how to boost the output using a PNP power transistor, but as you've never posted your schematic, we've no idea if you're following that.
As already suggested, breadboards aren't terribly great - stability is a problem, as is poor contacts - personally I never use them.
Just adding random components to a half baked circuit is not something which is going to lead to success.
(A technique reminiscent of "mstecha" for those who have been here for a few years!)
so according to a data sheet for the 7805, you should have small (1-10uf) bypass caps between the input pin and the ground pin, and from the output pin to the ground pin. you should also have the 7805 heat sinked because of the huge amount of voltage drop from 24 to 5 volts.
if you are going to use regulators and other analog chips, you should read the data sheet first. go to www.datasheetarchive.com and put in the part number you want a datasheet for
so according to a data sheet for the 7805, you should have small (1-10uf) bypass caps between the input pin and the ground pin, and from the output pin to the ground pin. you should also have the 7805 heat sinked because of the huge amount of voltage drop from 24 to 5 volts.
if you are going to use regulators and other analog chips, you should read the data sheet first. go to www.datasheetarchive.com and put in the part number you want a datasheet for
The calculation for the heating is simple: Volts x Amps= Watts.
The current in the regulator is very low because it is the base current of the transistor so the regulator does not get hot, but the transistor gets very hot with 8.5W so it will be burnt without a heatsink.