Power!!!

[Dragon Tamer]

i don't think that you understand, the output from the transformer has a high frequency oscolation combined with the sine wave. my power supply is going to be home made. i did an expiriment and learned that a voltage regulator with a current limiting resistor, connected to the base of a 3055 transistor, you get the same voltage out. all i need is to know the PNP equivalent of the 3055, i need a reliable function generator circuit (prefeerably somethin simple).

 

[Hayato]

I can't see the high freq. oscillation. Anyways if you are seeing it that's because of the 4700 uF electrolytic caps internal inductance. Use some 100nF bypass capacitors.

 

[Dragon Tamer]

ok i'll try that. i was kind of currios as to why so many poer supplies had those. my solution, (which made the problem worse) was to add a resistor to connect the caps to ground. Still no idea on what the PNP version of the 3055 is? i'm having trouble finding it on my own.

 

[Hayato]

The complementary part of 2N3055 is MJ2955.

4700 uF is too little for 10A.

 

[Dragon Tamer]

thanks for the part no. how do you know that 4700μF is too small?

 

[HiTech]

4700μF/ampere is the recommended value for the circuits posted further down the page in your posted link. 18 amps is going to involve some mighty large caps or a whole group of smaller ones bundled together! Looks like a fan is necessary to keep the heat generating components on the cool, calm side. None of those circuits are that great. There's no short circuit protection other than a fuse after the bridge rectifier itself. The transistors could very well go bust if current/heat climbs beyond limits. Search some more on Google using proper wording and you'll see many links to high current variable output power supplies.

 

[Dragon Tamer]

the fan has been taken into account, and there is a circuit in place that will keep the fan operating properly, and by modifying the speed. the circuit that i posted was just a general circuit, on the more refined diagram, there is a fuse on each output. i am also working on a short circuit detector for the circuit using a LM2902 op-amp. it should detect the short on either rail. it is going to referenced the unregulated voltage instead of one of the regulated voltages.