Test Light?

[Monk]

I been told at our local electronics (audio store) install store, not to use a "test light", if I don't know what I'm checking, and to use a meter, because a test light can screw up the on board computer stuff(my words not his). He said (after asked why) a light has resistance where the meter doesn't. So I know people use test lights all the time.

Should I use a meter instead?...........

[Ryanme17]

I been told at our local electronics (audio store) install store, not to use a "test light", if I don't know what I'm checking, and to use a meter, because a test light can screw up the on board computer stuff(my words not his). He said (after asked why) a light has resistance where the meter doesn't. So I know people use test lights all the time.

Should I use a meter instead?...........

I don't know about screwing up a board, but a multimeter costs less than $10 at harbor freight and will actually tell you your voltage or resistance.

[Macs06VFR]

Interesting. Never had a problem using my test light. The meter has resistance too (unless just testing connectivity), just probably not as much as a light.

I asked a couple IS/IT geeks I work with and they said they guess it's possible (damaging a board), but they've never seen it happen. Doesn't mean it couldn't. (They weren't much help, were they?)

Agree with Ryan though... Sear's often has really basic ones half off, or around $5-$8.

[Chev]

Wow, no one knows this? ............ Circuit Chev to the rescue!!!!!!!!

As usual the guy at the local electronics store is a complete idiot. Most of the time they hear something they do not understand and f$%^ it up when they try and repeat it.

A test light has resistance, yes.

A voltmeter has a whole ton of resistance...... way more than the test light. (an ideal voltmeter is infinitely resistant.)

So, your test light might allow enough electron flow to blow a component on a circuit board, but a voltmeter should have enough resistance to prevent such an occurrence.

[wera803]

If you have a choice, use a volt meter. It gives you actual measurements instead of "kind of a lit bulb" or a "bright lit bulb."

For testing things like headlights, I have used a test light when nothing else was available. For anything electronically sensitive (air bags, electronic boards, sensors, etc) I always use a multi-meter. The test light passes power through the bulb to light it and usually causes a small arc when connected, which can damage electronics.

[checksix]

A test light is low resistance and draws current through the circuit in which it is connected. This could damage delicate electronic circuits which typically run on very low currents and have very small traces. If you're just doing continuity measurements through plain old wire then a light is fine.

[soichiro]

A test light is just fine for quick ck.s and repair. If you are really diagnosing an electricsl problem you must have a voltmeter.

The kid at the store is an idiot.

[Monk]

Thx to all that answered......... I now own a multimeter, and have read all the directions....... Now to stick them in my ears and see if my brain has any current..... :laugh: ......Monk

[Macs06VFR]

Thx to all that answered......... I now own a multimeter, and have read all the directions....... Now to stick them in my ears and see if my brain has any current..... :laugh: ......Monk

Don't worry, it does. :blink:

[V4 Rosso]

As usual the guy at the local electronics store is a complete idiot. Most of the time they hear something they do not understand and f$%^ it up when they try and repeat it.

Maybe the electronics guy was correct, after all he tried to convince Monk to use a volt meter instead of a test light when working on delicate electronics. Maybe he expained to Monk that when checking voltage the multimeter has almost infinite resistance and almost zero when checking current, and Monk relayed it incorrectly to VFRD. Monk, are you sure he told you a volt meter (not amps) has no resistance?

[Monk]

As usual the guy at the local electronics store is a complete idiot. Most of the time they hear something they do not understand and f$%^ it up when they try and repeat it.

Maybe the electronics guy was correct, after all he tried to convince Monk to use a volt meter instead of a test light when working on delicate electronics. Maybe he expained to Monk that when checking voltage the multimeter has almost infinite resistance and almost zero when checking current, and Monk relayed it incorrectly to VFRD. Monk, are you sure he told you a volt meter (not amps) has no resistance?

I'm pretty sure, whatever was said that could have been wrong, came from me and not him. :laugh:

[belovian]

There are actually uses for both a test light and a multimeter. Where as it is said that a test light can be dangerous for sensitive electronics (I never seen this proven), it also has it's advantages. Here's the perfect example; If you were to test the wire between A battery and the starter or your car, and all but one of the copper strands in that 4 gauge wire were broken the multimeter would tell you that full battery voltage is getting from the batt. to the starter. However the car would never be able to start. Because a test light actually draws amps it helps detect resistance in circuits and weak connections. we used to use a headlight to check circuits the more amps they draw the better. if the light is dim you know there's a problem.

[Monk]

There are actually uses for both a test light and a multimeter. Where as it is said that a test light can be dangerous for sensitive electronics (I never seen this proven), it also has it's advantages. Here's the perfect example; If you were to test the wire between A battery and the starter or your car, and all but one of the copper strands in that 4 gauge wire were broken the multimeter would tell you that full battery voltage is getting from the batt. to the starter. However the car would never be able to start. Because a test light actually draws amps it helps detect resistance in circuits and weak connections. we used to use a headlight to check circuits the more amps they draw the better. if the light is dim you know there's a problem.

Another...... good to know...... Thx

[NorthernVFRDave]

Dont use them on your car, I've heard stories of people setting off airbags with them. :ohmy: :blink:

[Monk]

Dont use them on your car, I've heard stories of people setting off airbags with them. :ohmy: :ohmy:

Something tells me with your eletronic background, that you wouldn't believe any stories. So I'm-a guessing you're pulling my leg......... :blink:

[Tightwad]

test lights are great for what they are for, and shouldn't be used otherwise. Using them to follow your ignition wire or similar to find the voltage break is fine, using them on a circuit board of any kind is a no-no....plus meters are so cheap that my test light is at the bottom of a big electrical box where I am not likely to ever see it again.

Test lights also don't know the difference between 12.5 and 14.6 volts, but it makes a difference to us!

[V4 Rosso]

I have a Steinel mastercheck 2 that in a way combines a testlight with a voltage meter. It uses LEDs that indicate the voltage and has a high input resistance. A very handy tool.

[Macs06VFR]

Timely...

Harbor Freight has a 7 function multimeter on sale for $1.99 (limit 4). Granted, it's not a Fluke.

You need the coupon from their flyer. If your not on their mailing list, you can pick up eleventeen flyers at the store on the way in. I think the coupon is good for a couple weeks.

Bargain if I ever saw one.

[Tightwad]

Timely...

Harbor Freight has a 7 function multimeter on sale for $1.99 (limit 4). Granted, it's not a Fluke.

You need the coupon from their flyer. If your not on their mailing list, you can pick up eleventeen flyers at the store on the way in. I think the coupon is good for a couple weeks.

Bargain if I ever saw one.

That's a perfectly fine meter for 98% of what anyone would need to do. I use them in my garage for all but the most precise needs, and if I happen to drop one and then run it over, I am not out that much.

[Macs06VFR]

I have a couple too, along with a nicer one that stays in/on my workbench. I picked them (up on a similar deal) after the umteenth time wanting mine when out helping someone else with something where the 3 lb. sledge wasn't working so I figured it had to be electrical. :biggrin:

Like Tightwad said, they're throwaway if anything happens to them. I've had mine for at least a year, and have used them on occasion, so I got my money's worth. Heck, a replacement battery will cost more.