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 Power Supplies

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Cliff Jones
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PostSubject: Power Supplies   2011-04-14, 5:19 pm

Today, I Just received a power supply that an ARF member had for sale. It's HP 6227B, Very Happy supply. It has a range of 0-25 VDC & 0-2 amperes. It can be both a constant voltage and constant current source. It also has a crowbar to protect delicate electronics, such as working with a transistor radio that has a short some where, so the current can be limited to prevent further damage during trouble shooting.

I paid $75 for the unit and a cost of $25 shipping. It arrived by FEDEX unscathed. Very Happy
One supply wasn't working however, but after investigating the manual, there is a procedure to set the trip point. After following the instructions Rolling Eyes and making the front panel adjustments, all is working. Wink Smile

Now to find a neon lamp, or make an LED Pilot light. Sad Suspect scratch (Seller sent me one YEA!)[You must be registered and logged in to see this image.]

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PostSubject: Power supply missing   2014-08-04, 3:01 pm

I had a Wall Wart for my Yaesu that went missing, It was a 12Volt DC 2amps.

So after much searching :

I tried 3 others, First one was a wall wart switcher BIG MISTAKE inside was one cap for DC Filtering rated for 3 amps.

Second one was a Ritz Power supply, hooked up a speaker and lots of hum that was noticeable. So I decided to test further, opened the case, Had a huge Transformer, Bridge rectifier, two large Capacitor's, on/off switch, with pilot light.

Its output was labeled as "Magnetic Regulated" 13.8 VDC 8AMP. POWER SUPPLY.

So I asked for some Help on how this worked, most of my Ham buddies didn't have a clue.
But one of them had a slight understanding of how it was used. The term H e used was that it had a Ferro-Magnetic Transformer for regulation. Of the two caps, one is installed across one winding, its a bathtub style non-polarized cap.

This cap has to due with reducing the saturation level of the transformer. It is used mainly in industrial settings.
So it seems to regulate, but with the remaining electrolytic cap it has at least 2 Vpp of ripple, which isn't good for solid-state radios.  

So that one was also set aside. I did a lot of looking at small cheap power supplies, and most wont declare what the noise and ripple figures are. So I went back to my friend and told Him my situation, and He said He might have something that may work.

Well bless His Heart, He did have one that I could use. It is made and sold by POWER-ONE. It is a discontinued model, but the still make almost the same one as my new used one. ---> [You must be registered and logged in to see this link.]
I recommend this one.
It puts out 15 Volts DC, has a pot adjustment for voltage +/- 5% ( I set that to 13.3 VDC) Regulates ripple and noise to 5mV. WOW what a GEM.
New they sell for ~$40, boy that's a lot less than $70 for a replacement wall wart from Yaesu.

It has a 2 amp fuse on the DC side, I need to install one of maybe .25 amps on the input of the unit. Add a box, switch, LED for power indication and I am set. It is called an open frame power supply. I now will use this, as my Yaesu Power source.

I did some research on how to test power supplies, and gained some useful knowledge.
----------------
The final thought is you cannot just slap any available power supply into use without knowing specifications, as you might find out the hard way, that an expensive piece of Equipment my fry on you for lack of knowledge.

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FrankB
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PostSubject: DIY Wall Wart tester   2015-04-12, 7:24 pm

Most of us end up with gobs of wall warts and have no idea of they work or have bad conn. on the connector or at the transformer.
 You can build a test box with most of the common coaxial and mini phone jacks on it. Use a selector switch to select which voltage pilot lamp you have up to to 28 volts, and you will likely test any voltage wall wart you can find; AC or DC.
The jacks can all be wired in parallel too, as most wall warts only have 2 conn.; a hot and a gnd.

Set the lamp voltage to the correct one, Hook up the wall wart to the unit, plug in the wall wart and wiggle the wires at the conn and the wall wart housing.
Obviously, if the lamp stays solidly lit, the wall wart is OK, if it is intermittent the wall wart has bad wiring or a bad connector.

If you want to test some of the oddball voltage ones. like 18V, you can put 2 bulbs in series, or use the 28V bulb and remember the lamp will be dimmer.

Use your imagination. Heck, this box could easily be made pocket size, so you can take it with you to the thrift stores.
 (If you make it really nice, you might even be able to sell a copy of it to the thrift store so they can test them before selling.)

Remember, you can add almost any type of connector you want to this to test multiple types of the " non-standard" wall warts.
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PostSubject: Re: Power Supplies   2015-06-17, 9:07 pm

That's a good Idea. You could take to another step, more complicated of course. Add a multiple rotary switch with load resistors and two banana jacks, for use with either a voltmeter, or O'scope to check both voltage and voltage drop. Also the output could be AC INSTEAD OF DC. Some Walwarts are void of any voltage regulation. So a 12 volt set may start out as 18 volts, without the proper load, could damage some electronics.

The printed output is so tiny this would be a good method to check those outputs. The scope would also indicate whether the filtering was good or not.

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PostSubject: Re: Power Supplies   2015-06-17, 9:15 pm

For some strange reason the power light (neon) is now working? Might be a non-useage issue!

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