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Technical Topics => The RF Workbench => Topic started by: Matt285 on January 09, 2020, 2330 UTC

Title: Power supply voltage
Post by: Matt285 on January 09, 2020, 2330 UTC

I have a Tripp Lite PR-3A 12 volt power supply that puts out approx 13.4 volts. What would be the easiest and cost effective way to drop it down to 10/11 volts. For instance to run a Black Cat Systems 13mhz beacon? Thanks

Title: Re: Power supply voltage
Post by: Stretchyman on January 10, 2020, 0553 UTC

Couple of diodes.

Str.

Title: Re: Power supply voltage
Post by: NJQA on January 10, 2020, 1302 UTC

I agree that diodes would be the simplest way to do this...about a half volt drop for each diode in series.

If you need better regulation, another option would be a DC/DC buck converter (Similar to this: https://www.mpja.com/LM2596-Step-Down-Adjustable-15-37V-DC_DC-Converter/productinfo/30148+PS/ ).  These Chinese devices are available on eBay, Amazon, and other places for a couple of bucks.  You will need at least a couple of volts difference between the input and desired output voltage.  I would also be careful to filter the DC out of the converter to ensure it is clean and doesn’t modulate your transmitter carrier with noise.

You could also use a 7810 regulator chip, though if your input is 13.8 volts you might not have enough of a voltage difference for it to be reliable.

A fourth option might be possible.  Many power supplies have an internal adjustment to set the output voltage.  If your PR3 has this, you may be able to turn the output down far enough to meet your needs.

Title: Re: Power supply voltage
Post by: Josh on January 10, 2020, 1855 UTC

Some psus have at least two pots inside, one to adjust v and the other the crowbar trip point. If all you''re going to use on that psu is the bacon, set the psu pot to whatever voltage you can and enjoy.