10/29/2022 0 Comments Homebrew amplifier![]() The case for the power supply and the amplifier are identical, a 8x12x9 inch Hammond steel enclosure with alumminim front and rear panels. It was mounted on the back panel at the top right. The shunt has not yet been mounted in the picture that shows the Power Supply open. The panel meters came from as did the 25 Amp shunt for ammeter. This all happens in a fraction of a second. Once sufficient voltage is established on the 12 volt circuit, it trips the relay which shorts out the 10 ohm resistor. When the amplifier starts, there is a 10 ohm resistor that limits current into the transformer. The capacitor bank is capable of sourcing a lot of current at startup, so I use a relay to hold back the initial current. The color codes shown in the circuit diagram are for this transformer, but any high current 50 volt transformer will work. Like others who have built the EB104 amplifier, I purchased the transformer from Ameritron, part number 406-1246. The only difficult component to obtain for the power supply is the transformer. Keep them away from the electrolytic capacitors, which don't like to get hot. I used 25 watt power resistors and they seem to be fine. The bleeder resistors run quite hot because they draw about a third of an amp, which is 17 Watts at 50 Volts. You can find capacitors on ebay too at good prices sometimes. ![]() I purchased 10000uF 80V capacitors from at a reasonable price. The 50V supply is not regulated other than by a bank of capacitors and by a bleeder resistor. There is nothing complicated in the circuit. I also included 13.8 Volts for control circuits and 12 Volts for the fan. I designed it to produce 50 Volts at 25 Amps to supply the drains on the FETs and to supply the gate bias. While time consuming to build, the power supply was the easiest component to construct and test.
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