High Voltage, High Current Power Supply

I plan on building a solid state power amp, but don’t know which one yet. In the meantime, I figure I can go ahead and start making the PSU for my future amplifier.

I tried iTead Mall to place my order for (5) PSU boards. So far, I’m pleased with iTead’s quality, though there was some miscommunication with them. They didn’t update my order status for 2 weeks, it still says “Processing” on their website, when in reality, they’ve already shipped my order but didn’t email me a tracking #. Anyway, once I submitted a ticket, they’ve been very responsive and apologetic. Then by coincidence, I got my PCB in the mail the day after I complained. I will be using them again in the future.

So basically, I want the PSU to be able to cater to higher voltages, like +/-80 or 90VDC… so I made sure there’s enough room on the board to allow the use of bigger capacitor, 100+V rated or more.

The PSU board can accept either spade connectors, or terminal blocks.

I’m using Ultra Fast Recovery Rectifiers, bypassed with Panasonic Safety Class X2 polyester film caps (250V rated). I have heatsinks on the rectifiers but they don’t need it. They’re cool to the touch.

There are green LED indicators under the fuse on the DC output, so if the fuse blows, the LED also goes out and you can quickly see the problem. There’s also a couple of AC fuses.

It’s basically just a simple power supply, albeit using high current/high voltage parts.

Step 1: Bare PCB … ready for population and build.

STEP 2: Insert 0.1uf / 100V ceramic caps. These are bypass capacitors for the DC output. If you need to add more bypass caps, you can solder them underneath the board across the capacitor terminals.

STEP 3: These are the current-limiting resistors for the LED power indicator. The 3mm LEDs are located under the fuse on the DC output.

STEP 4: Fuse holder clips…. 2 fuses for the AC primary side, and 2 fuses for the DC side. Depending on the VA size of your power transformer, pick the appropriate/correct fuse rating.

STEP 5: These are the 4x Ultra Fast Recovery Rectifiers, rated 600V Reverse Voltage, 10Amps. Added TO-220 heatsinks just to be sure. Yes, I know… it’s overkill.

STEP 6: I made a mistake of trusting the datasheet… the component size is correct but the lead spacing is wider than I expected. So here’s a temporary fix to make it work with the PCB.

STEP 7: These are the (4x) Safety Polyester Film Capacitors, rated 250Volts, Class X2. Each capacitor is connected across each Rectifier Diode.

STEP 8: Terminal Blocks with screws. Heavy-duty, rated up to 32Amp, and can handle up to AWG#10 gauge wire. AC side accepts dual secondaries from power transformer. DC side outputs split voltage, V+, V- and GND.

STEP 9: 10,000uf capacitors for DC Filtering. Since this is a split power supply, there’s 20,000uf for each V+ or V- voltage rail. Use the appropriate voltage rated capacitor matched to the power transformer, and DC output you need. The higher the capacitor voltage rating, the more expensive it gets. There’s enough room on the board to accept bigger diameter/higher voltage capacitors up to 100Volts DC rated or more.

Another view of the finished High Voltage Power Supply.

Size comparison of finished High Voltage, High Current Power Supply compared to an iPad Air. PSU weighs in at 11.1 ounces.

Power Supply Testing.

Ripple voltage is 11.5mVolts peak-to-peak, 25V+25 AC input, 35.4VDC + 35.4VDC output.

The above screenshot for ripple is wrong. I’m basically measuring noise in the environment, instead of the actual PSU ripple. Here are updated screenshots.

There you go, that’s more like it… 2.5mVpp ripple.