# What's in an electronics hobbyist's toolbox?

Pretty nifty rig! My bad, VR Voltage regulator.. since they often come in the TO220 package

davenn
Gold Member
Pretty nifty rig! My bad, VR Voltage regulator.. since they often come in the TO220 package

no, not voltage regulators and other IC's
they are complex devices with multiple semiconductors and other parts

I have a really nice linear slide rule.. about all I can do with it is multiply/divide though.. it's got about 20 darned scales on it for everything from trig, logs, roots, and a bunch of stuff I'm not sure what it is

Thanks, though its been sitting in it's case for 20 years, I suspect it'll sit there for 20 more years.

Good link, I've bookmarked it so I can come back to it in 2050 :P... I'd like to learn it just for curiosities sake

jedishrfu
Mentor
Thanks, though its been sitting in it's case for 20 years, I suspect it'll sit there for 20 more years.

Good link, I've bookmarked it so I can come back to it in 2050 :P... I'd like to learn it just for curiosities sake

The numbers might fade away as do so many things when they are no longer wanted. :-(

Cheerup, Mr Slide Rule! We have hope that your owner will reconsider his insensitive and uncaring view of your worth while he browses this post with his superfast and really cool smart phone.

PS: Actually its more likely the web page will vanish.

RaulTheUCSCSlug
Gold Member
Has anybody said coffee/Red Bull yet?

berkeman
Mentor
Has anybody said coffee/Red Bull yet?
LOL. But what's wrong with that suggestion if you do rework on your SMT circuits under a binocular microscope?

- nail polish. Handily packaged universal coating material.
- flux were already mentioned several times - however: what I pack is some real 'rosin' gel flux. I admit it's old fashioned, but we had some hard time once when we discovered that the common OA fluxes are actually not very good and quite moist sensitive when it comes to insulation...

I use a ESD mat and grounded wrist clip when working with more static sensitive parts including the assembly of circuit board based prototypes.

berkeman
jim hardy
Gold Member
Dearly Missed
grounded wrist clip
if you home-brew one be sure to include about a megohm resistor to limit current through your wrist. You don't want it to become the preferred path for accidental fault current.

NTL2009 and nsaspook
Thanks Jim, I have a ground system that I bought that has a 1 Mega ohm resistor in the wire from my wrist strap to a eyelet on my mat. From that point it is connected to earth ground via a receptacle. The 1 Mega ohm resistor should safely limit the current to 2ma or so if a 2Kv potential was present at my wrist. Since my matt is also at earth ground, the charge should be carried away from ESD sensitive parts on the mat itself. I invite any further comments or suggestions that you may have

jim hardy
jim hardy
Gold Member
Dearly Missed
I invite any further comments or suggestions that you may have

Good job. You explained it well.
If your finger gets into 120 VAC housepower in something you're working on , you won't have a dead short to ground through your wrist. Your clothes and shoes will provide some protection.

The wristband is a drain for miniscule static currents not a personnel safety ground. It protects the electronic parts on your bench, not you.
Never bypass that 1 meg resistor .

Thanks for considering my comment - helps an old guy feel useful.

old jim

If your finger gets into 120 VAC housepower in something you're working on , you won't have a dead short to ground through your wrist. Your clothes and shoes will provide some protection.

Since possible shock via mains AC has been mentioned, I'd make a further recommendation for anyone regularly working on devices that require mains AC. In my case, it's guitar amplifiers, but it could be any audio or household appliance. The recommendation is this:

1) Assuming you have a bench with a line of outlets running above it, replace the outlet closest to the circuit breaker with a GFCI outlet; wire it up so that the outlets further outboard are a load on that GFCI outlet, thus all outlets are protected. Be prepared to test regularly since eventually these can get tired, just like a breaker can get tired.

2) If you travel to work on mains AC appliances, consider getting (a) a portable GFCI outlet, and (b) whatever you consider adequate for testing for incorrectly wired outlets - you want to be able to rule out no ground, bootlegged, or reverse-bootlegged, etc. I'm tired at the moment otherwise I'd look up all the conditions. To really test them all you need a pretty expensive tool that I am blanking on at the moment, but you can test most of the conditions with a simple neon proximity voltage tester - one of those pen-like devices - if you know how. I carry one in my toolbox along with instructions on how to use it for such purposes.

People may not like GFCI since you can occasionally have a false trip; but it is far safer than relying on a 15A or 20A breaker to kill AC before you can get badly hurt. Of course it can't help with other issues, e.g. if you are working with high voltage DC and decide to interpose some part of your body into the circuit; but still worth it. Lots of appliances, amplifiers, etc., are built such that bare AC terminals inside the box are quite near things you might want to be working on. There are work procedures to make this less unsafe, but it's still nice to have a backup safety measure.

jim hardy
Gold Member
Dearly Missed
To really test them all you need a pretty expensive tool that I am blanking on at the moment,

around eight bucks at Walmart

View attachment 113298
around eight bucks at Walmart

I'm surprised you would recommend this, given that you're an EE and probably have about 5,000 times the knowledge I do about circuits, instruments etc.? Based on extensive reading & discussion with EE's, shop techs, etc. on other forums, I'd suggest that the cheapie detectors are perhaps the worst of the available choices. They miss the most dangerous scenario, the reverse bootleg, plus at least one other. And they might tell you that your ground is OK when it's not.

The expensive gadget I referred to is the one that can actually check the quality of a ground in a meaningful way; I just went and re-looked it up. It's called an "earth-ground resistance tester" and mostly the only people who need it are field technicians. A nice selection of models can be found on Amazon, from $92 up to$1,529. However it's only for a very specific and limited use; and besides it's possible in most ordinary homes to check ground quality through more ordinary means. I think the field techs are probably sussing out industrial situations and also can't afford to waste time.

Here's links on this topic, varying in quality; the one I like best is the "Shock Zone", second link; it shows how to use the neon voltage proximity tester to check specifically for bootleg. And obviously you can use a DMM; plus inspect; etc. etc. You don't have to buy the super-expensive gadget, but you can do better than the \$8 thingie.

https://en.wikipedia.org/wiki/Receptacle_tester#Safety

http://www.thecircuitdetective.com/test.htm

And there are other sources of expert info as well if one wants to spend the time, e.g. electrical inspectors write about this sort of thing with varying degrees of authority.

From the Wikipedia article -
Simple three light testers cannot detect two potentially serious house wiring errors: (1) neutral and ground reversed at the receptacle. (2) a bootleg ground, where the neutral and ground pins have been connected together at the receptacle. This may be done by someone fitting 3-prong receptacles on a circuit that has no ground wire.

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jim hardy
Gold Member
Dearly Missed
The expensive gadget I referred to is the one that can actually check the quality of a ground in a meaningful way; I just went and re-looked it up.

Thanks !

berkeman
Mentor
I'm surprised you would recommend this, given that you're an EE and probably have about 5,000 times the knowledge I do about circuits, instruments etc.?
I use the same device, but will read your links when I have time. Thanks for posting them.

I use the same device

I was using it too, then via a forum w/ some EEs/guitar techs on it, heard about the potential issues.

I would be interested in hearing what other people think when they have a chance. I trust the materials I've read, and have done some thinking and experimenting; but I'm not myself an expert.

jim hardy
Gold Member
Dearly Missed
I'd suggest that the cheapie detectors are perhaps the worst of the available choices.

OTOH they'll find 99% of anything an average homeowner can fix by himself.

And a RPBG, the dangerous mis-connection, will announce itself first time you touch an appliance that's plugged into it.

If a fellow's got an old house with only two wire Romex (no earth conductor) and all his three prong outlets were "bootlegged"(a new term to me) by some unscrupulous prior owner, then as you say the cheapie won't show that. First receptacle he opens will make it obvious, though. Anybody sneaky enough to do that would probably do a good job so as to not get caught.

If the third prong isn't "bootlegged' the cheapie tester will find it.

My utility room is wired that way, no ground wire but not bootlegged.
That room was added, i found out, by a scalawag contractor forty years ago who'd got a pile of two wire romex sans ground real cheap.. Some of it wound up in my utility room. He just left the ground prong unconnected.
When i found that, which i did because the three light checker showed open ground, i replaced his three-prong/non-"bootlegged" outlets with old fashioned two prong ones and put in three-to-two cheaters. That way it's obviously a workaround for obsolete wiring that lacks an earthing conductor.

I grounded the washing machine to the copper water pipe . Noblesse Oblige.
Most electric tools and appliances nowadays are double insulated and come with two prong cords so the obsolete wiring in that one room isn't much of an inconvenience. Re-paneling that room is on the "Do List" , will rewire when walls are open for that .
Rest of the house, built around 1960, is 12/3 grounded. I did find more than one hot-neutrals swapped, though.

To check ground integrity i make a "poor man's test fixture",
consisting of a 100 watt lightbulb in a lamp socket,
center of socket connected (through a switch) to hot of course
and barrel of socket switchable(a separate switch) to either neutral or earthing conductor.
Lightbulb should light with neutral selected to neutral, of course,
and also should light with neutral switched to earthing conductor unless it's on a GFCI circuit.
Voltage measurements between Neutral and Earthing conductor give me a clue as to condition of those two paths.
I've found and fixed a lot of loose connections in old buildings that way.
But that's something you shouldn't try unless you're very familiar with electrical safety.

So i think every homeowner ought to have one of those cheapie receptacle checkers in his toolbox or desk drawer and know how to use it.
It's not perfect but way better than not looking at all.

I got some 12/2 Romex sans ground by accident.
Found it's got the /U insulation for wet locations so am using it for low voltage lights out to the Barbecue/Tiki area.. That's all it's good for.

old jim

PS Thanks for those links they're real practical.
A fellow should print out that "Circuit Detective" one on how to use the three light tester and keep it with his tester.
In this day and age homeowners should understand household wiring.

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Thanks for the response at length, Jim.

To check ground integrity i make a "poor man's test fixture",
consisting of a 100 watt lightbulb in a lamp socket,
center of socket connected to hot and barrel of socket switchable to either neutral or earthing conductor.
Lightbulb should light with neutral selected to neutral, of course,
and also should light with neutral switched to earthing conductor unless it's on a GFCI circuit.
Voltage measurements between Neutral and Earthing conductor give me a clue as to condition of those two paths.
I've found and fixed a lot of loose connections in old buildings that way.
But that's something you shouldn't try unless you're very familiar with electrical safety.

Yes, this is one of "ordinary means" I was referring to; I agree with the caveat.

As for the plugin tester vs. other options, I really like the procedure that the Shock Zone guy describes for the neon light gadget. Ironically the neon light gadget gets more abuse than the plugin does. I now prefer the neon light (plus instructions), along with a DMM and whatever "ordinary means" make sense for the situation.

The bootleg situation becomes a concern if you're, say, a roadie helping your band set up at some venue. It becomes helpful to have a good way of detecting the worst problems quickly. I learned about this as an issue - including the various "shocking" incidents on stage that have now & then maimed and/or killed electric guitarists - via a forum, http://www.thegearpage.net, that has a very active sub-forum on guitar amp building, modifying, and repair. I've done a fair amount of hobbyist work w/ amps over the past few years, so workshop & home electrical safety have become important for me.

jim hardy
Gold Member
Dearly Missed
I really like the procedure that the Shock Zone guy describes for the neon light gadget.

That's indeed a good article. All of those links are good.

When things get confusing I revert to the voltmeter to earth method he describes. I use a cheap analog meter because it's not very sensitive so draws enough current , about a millliamp, to not get confused by stray capacitance.

I never thought about musical stage setups for i was just never was around them. I'll bet you have seen a LOT of near misses and have some great experiences you could relate.

old jim

Thanks Jim and usablethough for your input

jim hardy
Can't see this one mentioned:

Magnetic trays. The kind auto-mechanics use. Annoying when you brush a bunch of carefully laid out screws everywhere, and you wanted them to go back into the holes they came out of. I prefer pushing screws into foam, but trays are useful when working in awkward positions.