I need to replace an AC adapter

[sam E]

IIRC it's a flammable string they used to use to set off dynamite.

[snip]

[gregz]

225mA machine?

I hooked up a switcher to a cb radio, very horrible noise which also made the circuitry act funny. With the application of 4 more ferrite devices, I got it usable.

Greg

[krw]

225mA machine?

Fix your radio.

[gregz]

225mA machine?

Nothing wrong with radio. The switcher was not designed for radios.

Greg

[gregz]

Forgot to add. The noise is common mode, not differential. Common mode noise goes right through the radio out to the antenna transmission line to antenna. Also into any capacitive grounding of radio system. This all induces noise into the cb band. Really get real.

Greg

[CRNG]

On Mon, 23 Jul 2012 18:40:38 -0600, "PV" wrote in Re Re: I need to replace an AC adapter:

+1

[clare]

225mA machine?

Actually, MANY are. I use a switcher on the aircraft radio with no issues.

[krw]

225mA machine?

If the radio won't work with switcher noise it won't work in any noisy environment, either. If it isn't broken, it's crap.

[Ralph Mowery]

Some switching supplies generate a lot of noise that is in the radio frequency area. They will power devices fine, but at the same time if you want to receive something that some of the RF noise appears on, there will be a problem. Some of the battery chargers around the house RF generate noise even when not charging a battery. Some small fans such as in a computer that work on DC have an internal switching supply of sorts that can also generate RF noise over a wide frequency rnge.

[mike]

snipped bad advice.

That's exactly the point. Most devices ARE CRAP. They're designed to work with the supplied accessories at the lowest possible price.

The wall wart is often an integral part of the system design for cheapo devices...especially where battery charging is involved.

I've hosted many a design review where some very smart engineer was oblivious to the wider ramifications his "clever" design.

We know exactly ZERO about the "machine" being powered. ANY advice on changing the wall wart is premature.

Making random WILD guesses about what is or isn't compatible is irresponsible.

Most of the time, it's ok. But you're not the one who suffers the consequences when it's not.

Safer to ask the OP what he's got before pontificating, don't you think?

[krw]

If that's affecting your radio, throw it away and buy a better one.

Ditto.

[krw]

If a device will be affected by a switching power supply it will be similarly affected by other noise in the vicinity. If it's that crappy, it's useless. Get rid of it.

Utter nonsense. Wall warts are generic, *seldom* designed for a specific product.

Haven't we all.

Utter nonsense.

Then we might just as well shut down this forum. There is never enough information to be 100% sure that the solution is the best.

Horseshit.

You're an ass.

[gregz]

I built a lot of stuff for medical research, which is very sensitive to LF noise, especially 60 Hz. I found most of the switcher supplies from jameco were great at not producing noise in that area.

On cb I noticed what sounded like a charge and discharge, loud cracking. Sounded like a power line leak. I went all around house finding strange places where the noise showed up. Outside the noise was coming from power lines. Walked up the street 300 feet, the noise was the strongest. Back at the house I was convinced there was still something in the house. Started flipping breakers. Found it. but didn't seem logical. My kitchen computer area had a power strip. Look down at sears lithium power drill charger I plugged in day before. Pulled plug, got it. The noise was not strong at the device. I'm still wondering if neighbor has similar device up the street where it was the strongest.

Greg