The right tool for electrical testing

Tom Wesenberg

Tom Wesenberg

Well-known member
For anyone wanting to do electrical testing on your Model A or garage outlets, etc. I always recommend a good ANALOG meter. In today's paper I see Menards has a GB brand multimeter with a built in buzzer continuity check on sale for 1/2 price of $9.94. From the small picture it looks like it may be the same meter I am using, a GB model GMT-19A, which also has a built in batter check for 1.5 and 9 volt batteries.

I haven't been to the store yet, because we got a layer of glare ice overnight and it isn't worth the risk of going out right now, but I'm going to buy one to keep in the car.
 
I agree that analog is probably better, but I got a decent
digital from Harbor Freight for about 2.75 that works just dandy
and it will do all of the above. JMHO

Jack
 

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Jack '29 Sport Coupe said:
I agree that analog is probably better, but I got a decent
digital from Harbor Freight for about 2.75 that works just dandy
and it will do all of the above. JMHO

Jack
Click to expand...

I picked up one just like that the other day just because I had one of those FREE H/F coupons for it. It doesn't zero out on the 2 lowest ohms scales.
 
For some things I prefer a quality analog meter. For most of my work I use a Fluke 177 which is around a $250 digital meter. Often I will use my Simpson 260 7P which is a $300 analog meter. There are times the analog meter is easier for me to understand.

Typically I use the analog meter when measuring current, or doing tuner alignments. Although a good digital meter like the Fluke 177 has a "analog like" bar at the bottom which updates pretty fast. A decent oscilloscope with digital readout can be very handy as well.

I own these meters because I work on electronics mainly and wouldn't expect most people to buy them for working on the A. I don't know if I could tolerate a $10 meter though. I would certainly recommend a cheap analog over a cheap digital. The cheap digitals are WAY too slow.

Keep in mind, if you spend some money on a meter its like any other tool, something you will have forever.
 
While on that subject, I am wondering what would make a good power source for on the bench testing of horns, lights, wipers, etc., if you don't have a battery handy? Could on old charger set on 6 volts work?
 
ursus said:
While on that subject, I am wondering what would make a good power source for on the bench testing of horns, lights, wipers, etc., if you don't have a battery handy? Could on old charger set on 6 volts work?
Click to expand...

A 6 volt battery charger will work if it has enough amps. A properly adjusted Model A horn draws about 5 amps running, and will take a bit more to get it spinning, so you may need a 10 amp 6 volt charger.
 
I'll never understand electricity, but read all these posts, like a visit to the snake house in the zoo, hate snakes too. What is the "Speed' thing you are talking about? :confused:
MrTube said:
The cheap digitals are WAY too slow.

Keep in mind, if you spend some money on a meter its like any other tool, something you will have forever.
Click to expand...
 
Roadster62 said:
What is the "Speed' thing you are talking about? :confused:
Click to expand...

In my opinion, for model a's meter speed means little.

With the analog (needle) meter the needle moves because of the electricity that it is connected to. The more electricity the more movement.

While you might think that a digital meter is the same thing, the digital meter samples the electricity, measures it, converts it to a digital readout and then goes out to sample the electricity again, over and over. The time it takes (speed) to go through this loop allows the meter to miss short term spikes in the readings.
 
I do not find a battery charger to be a suitable substitute for a car battery when testing parts. First, the output is a series of half sine waves, not a constant DC. Motors, like wipers and horns, and anything that has a magnetic coil in it like relays do not react the same way as they do to linear DC. If you just want to see if something is working or not, that may be OK, but if you want a realistic performance evaluation or want to make adjustments, you will have problems. Second, many chargers have only half-wave rectifiers, not full wave. They do that intentionally, to permit zero current time to permit plate degassing in standard, non-maintenance free batteries. That's necessary to achieve a an even chemical reaction on the plates, extending the service life of the battery. If you have a half-wave charger the output is like ^-^-^-^-^. The battery charges very well, but lights, motors, etc will only see a time averaged voltage of about 4 volts (8V for a 12V charger).
 
ursus said:
While on that subject, I am wondering what would make a good power source for on the bench testing of horns, lights, wipers, etc., if you don't have a battery handy? Could on old charger set on 6 volts work?
Click to expand...
If I just want to see if something works I usually grab a spare battery for my 9.6V cordless drill.
 
Pierce Simpson 260P is hard to beat. Yes its big and bulky but nothing like watching that meter swing. Bought mine in 1974 and wouldn't take for it.
 
Roadster62 said:
Have any two electrical guys ever agreed on an electrical question, and given the exact same answer?
Click to expand...

I agree completely with what Mike said and I would only use a 6 volt car battery to adjust the horn. In fact the cover needs to be screwed in place during final adjustment, because the cover screw pulls on the motor frame and can change the tone.

In this case ursus just wanted something to use for testing to see if the horn, lights and wiper works, and a 6 volt charger of at least 10 amps should fill those needs.
 
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