Search found 525 matches

by sofaspud
Wed Dec 02, 2009 2:10 pm
Forum: General Discussion
Topic: cleaning battery contacts in solid state devices
Replies: 7
Views: 1158

Re: cleaning battery contacts in solid state devices

You can buy an eraser at the hobby shop that is used for cleaning a slot car track. Fixes essentially the same problem. A relay-contact burnishing tool can also be used when the oxide gets heavy. It's very similar to a miniature fingernail emory board, which you might already have on hand. {no pun i...
by sofaspud
Tue Dec 01, 2009 4:31 pm
Forum: General Discussion
Topic: why infra-red and not visible led?
Replies: 5
Views: 839

Re: why infra-red and not visible led?

I took a look at the 4N25 datasheet; it does indeed operate in the IR region. Curiosity then got the better of me. From what I could come up with, infrared is used because it optimizes photosensitivity (e.g. wavelength matching, response time, and all that good etc. stuff). This ' Use Of Phototransi...
by sofaspud
Mon Nov 30, 2009 2:32 pm
Forum: General Discussion
Topic: why infra-red and not visible led?
Replies: 5
Views: 839

Re: why infra-red and not visible led?

The only two reasonable answers I could come up with are 1) the ambient light theory and 2) it is easier/cheaper to achieve a wavelength match in the infrared spectrum. The first just seems sensible, the second is more semiconductor implantation physics that I've never really looked into. I wonder w...
by sofaspud
Mon Nov 30, 2009 2:21 pm
Forum: General Discussion
Topic: SIGNAL TRACER
Replies: 8
Views: 1568

Re: SIGNAL TRACER

The OP stated "I have a stand alone amp that it can be plugged into" not realizing that he already had the audio signal tracer being requested. All that's needed is the probes. Probably the easiest thing to do is replace the amp's input jack(s) with banana jacks and use regular ol' DVM probes. An al...
by sofaspud
Mon Nov 30, 2009 12:58 pm
Forum: General Discussion
Topic: Inductance Measurement, Meter Sources?
Replies: 10
Views: 1149

Re: Inductance Measurement, Meter Sources?

A similar or identical L-meter is shown in the 2002 ARRL Handbook. The Spiwak article was available for a while as
a pdf file from the Poptronix website. I had gathered the parts together, but it's still waiting to be built. It's the
best non-microcontroller design I could find at that time.
by sofaspud
Mon Nov 09, 2009 5:04 pm
Forum: General Discussion
Topic: Free TV Schematics
Replies: 21
Views: 3797

Re: Free TV Schematics

I'd give eServiceInfo.com a try too.
by sofaspud
Mon Nov 09, 2009 4:59 pm
Forum: General Discussion
Topic: Tool Time
Replies: 25
Views: 2461

Re: Tool Time

The wrench types shown at the Park Tool and Amazon links...
instead of grinding the face, these edges can be ground so the wrench is not so wide.
Or request a recommendation from the manufacturer (Omron, Panasonic, etc.)
by sofaspud
Sun Nov 08, 2009 4:38 pm
Forum: General Discussion
Topic: Tool Time
Replies: 25
Views: 2461

Re: Tool Time

Hmmm... I'm not even sure what the standard nut size is for switches and pots. 3/8"? For a store-bought solution, bicycle wrenches seem like an excellent idea. I'm not sure, though, that they'd be available at such a small size as 3/8", which is considerably smaller than the usual pedal/cassette/hea...
by sofaspud
Fri Nov 06, 2009 5:11 pm
Forum: General Discussion
Topic: home brew CRT rejuvinator ?
Replies: 11
Views: 1171

Re: home brew CRT rejuvinator ?

This is maybe one of those "good news/bad news" situations, but among my circuits collection I have what the designer calls a Picture Tube Tester/Rejuvenator . I believe I got it from a ~40 year old television book. Unfortunately I won't have access to it until around the Thanksgiving holiday. Remin...
by sofaspud
Wed Nov 04, 2009 2:58 pm
Forum: General Discussion
Topic: Looking for a flyback
Replies: 2
Views: 510

Re: Looking for a flyback

Your best bet may be to obtain the specs for the Dugo part, then see what kind of equivalent you can order
from someone like Dalbani or the recently mentioned MAT Electronics.
by sofaspud
Wed Nov 04, 2009 2:49 pm
Forum: General Discussion
Topic: Ripple Cancellation
Replies: 29
Views: 2833

Re: Ripple Cancellation

2.5MHz ripple from a power supply? I don't recall ever running across anything like that. Are modern switchers
running that fast, or is this some "non-standard" app? The aforementioned LC filters and an LDO regulator with
good ripple rejection are the only options I'm aware of.
by sofaspud
Wed Nov 04, 2009 8:47 am
Forum: Computer Programming
Topic: Unknown Disc Usage
Replies: 21
Views: 2635

Re: Unknown Disc Usage

If you were interested in my method of archiving files and making a text file of backup-disc contents, I just learned of some helpful software. Courtesy of Don Lancaster and his What's New? blog. He says, -October 24, 2009 I was surprised to find out that there is no direct or obvious way in Windows...
by sofaspud
Thu Oct 29, 2009 3:58 am
Forum: General Discussion
Topic: Signal Tracer revisited.......
Replies: 26
Views: 2881

Re: Signal Tracer revisited.......

Utilizing the radio's existing circuitry is a good plan. I'm not dead set on the LM386. I'd just tap into the already-built-and-wired volume control/amp/speaker of the radio. If the 1458 has a 40mA output source capability (my datasheet neglects to include this spec), using I^2R gives a measly 12.8m...
by sofaspud
Tue Oct 27, 2009 4:27 pm
Forum: General Discussion
Topic: Etchant solution
Replies: 19
Views: 2877

Re: Etchant solution

Hmmm... y'all are making a strong case. I have a buddy in the pool business so I could get
the acid for next to nothing. He's given me some before - the stuff will easily remove hard
water deposits and make your faucet fixtures look like new! :lol:
by sofaspud
Tue Oct 27, 2009 4:07 pm
Forum: General Discussion
Topic: Signal Tracer revisited.......
Replies: 26
Views: 2881

Re: Signal Tracer revisited.......

Does your "new" radio include a LM386 chip? For driving a speaker, I think I'd use it instead of the 1458. I'm not sure what kind of output the 1458 can deliver to a loudspeaker, but it's probably not much. The circuit as is provides about 300X amplification; the LM386 can give 200X with a simpler c...