Do it yourself

Quote: Dalex64

I have not seen one that does not merely complete a circuit using the probes.

In a cheap multimeter, that just completes the connection of a single 1.5v dc battery to either an led, the sweep meter, or a transistor controlling a beeper.

Here are several designs

https://www.brighthubengineering.com/diy-electronics-devices/67224-build-yourself-a-simple-continuity-tester/

Also, a signal has voltage.

I knew you wouldn't like that. I don't think they do induce a voltage, as they are used in the most sensitive of circuitry that would fault when any voltage may be applied?

If they do induce a voltage,[ which I don't think they do] in Face's hypothetical wire/light/wire/open, battery, introducing a [dc] voltage [continuity tester] between the closest side of the light, which was on the energized side of the fault should allow us to measure the voltage and expect the voltage to be additive, as we have only made a longer series circuit. A voltage tester then should be able to be applied and the total volts recorded should be the battery total + the continuity tester's voltage.

https://en.wikipedia.org/wiki/Signal

https://www.techopedia.com/definition/14154/signal-electronics

fwiw, the multi testers that I've opened up have a battery and a fuse in them, if the meter is accidentally left toggled to continuity when checking a live circuit, often the fuse will blow. I'm certain more than one person has went on to think their meter was working when it was not after the fuse had blown. A person that deals with these meters frequently learns to test them before and after use, for that reason. Check the checker.

Quote: Face

First, my issue is a spark plug, which unlike a simple light, requires a clean shot of high power to function, as opposed to a light which will work if a just trickle gets through. As such, my problem could be EITHER a broken circuit caused by faulty ground / broken wire / bad connection / bad part, OR it could be voltage drop due to bad connection / short / wire seep / etc. That sound right? Pretty sure it's solid on the auto side (some power but not enough could mean no spark), I'm just making sure the magic side is sound.

https://nationalmaglab.org/education/magnet-academy/watch-play/interactive/ignition-coil

A coil is just a transformer, changing voltage at one potential to voltage at another potential. Any more and I'm probably guessing. I see a spark plug as a little insulator holding a hot lead connected to a firing pin, when energized at 40k, the spark jumps across to the lil bent part, where we set the gap. It is just momentarily doing the same thing a welder does, only for a split second.

I think a coil is a coil is a coil? Look it up and see if the output voltage is the same on this one versus one for an old Chevy? They all have to make about the same output voltage to jump the air gap, the different shapes are for logistics imo. The input voltage to the low side of the coil is probably the same as your ignition voltage, 12.3 or whatever your system is running? I think that's the way it works? : )

Quote:

So I've got to find out which. If I've got this right, then there's two ways, one for each possible problem. For a too low voltage situation, I would use the above voltmeter test from the video. Test the battery to get my base, then start testing connections and implements downstream from there between connection points. That makes sense to ensure power's getting where it needs to be, and I'm already aware that while the batt maybe ~13v, the different implements' values may be severely different. A TPS, for example, ranges from 0.0v to ~ 4.8v, depending on throttle position. So make sure I'm still around 13v everywhere leading up to whatever device, then ensure I get the proper readings FROM that device. Sounds good and familiar. But if that's correct... thinking out loud here... this test has to be done with the power ON. So if I try, and I get nothing... and I know the batt is charged... then it's a continuity problem... yes?

If it were me at this point, or several points back I would have went brute force and put the volt meter away. Just kidding. Can you Jerry rig another coil [from dang near anything] into place and bypass your coil, and see if that lights the fire? Don't even have to run it through the plug. Just disconnect the wire under the boot on the top side of the plug and watch for spark when it's turning over? Old school, we would pull the plug and do the same thing and see if spark jumped across the plug electrode.

If another coil doesn't ignite across the electodes +/-, than it probably isn't getting the juice from.....the brain? Or what tells this coil when to fire, there is no distributor anymore correct, everything's in that little brain afaik.

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And for THAT, I would use an ohmmeter with the power OFF. And with this I should be able to see if a wire is whole and the connection secure (no resistance), see that devices are sound (their prescribed resistances) or whether the circuit itself is entirely broken (complete resistance).

What are you trying to figure here, the resistance of porcelain? It should be close to infinite.

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That sounds right? Tell me it's right.

You don't know who your asking. I can be bought, just haven't settled on a price.

Quote: petroglyph

I knew you wouldn't like that. I don't think they do induce a voltage, as they are used in the most sensitive of circuitry that would fault when any voltage may be applied?

If they do induce a voltage,[ which I don't think they do] in Face's hypothetical wire/light/wire/open, battery, introducing a [dc] voltage [continuity tester] between the closest side of the light, which was on the energized side of the fault should allow us to measure the voltage and expect the voltage to be additive, as we have only made a longer series circuit. A voltage tester then should be able to be applied and the total volts recorded should be the battery total + the continuity tester's voltage.

https://en.wikipedia.org/wiki/Signal

https://www.techopedia.com/definition/14154/signal-electronics

fwiw, the multi testers that I've opened up have a battery and a fuse in them, if the meter is accidentally left toggled to continuity when checking a live circuit, often the fuse will blow. I'm certain more than one person has went on to think their meter was working when it was not after the fuse had blown. A person that deals with these meters frequently learns to test them before and after use, for that reason. Check the checker.

How can you have a signal without voltage?

The more expensive stuff, which I did just read about, uses lower voltage for more sensitive electronics.

In the cheap meters with a 1.5v battery, that voltage level and the limited current it is capable of producing won't hurt anything.

Anyway, I see what you believe, and after doing some research, I disagree with you.

Quote: petroglyph

https://nationalmaglab.org/education/magnet-academy/watch-play/interactive/ignition-coil

A coil is just a transformer, changing voltage at one potential to voltage at another potential. Any more and I'm probably guessing. I see a spark plug as a little insulator holding a hot lead connected to a firing pin, when energized at 40k, the spark jumps across to the lil bent part, where we set the gap. It is just momentarily doing the same thing a welder does, only for a split second.

I think a coil is a coil is a coil? Look it up and see if the output voltage is the same on this one versus one for an old Chevy? They all have to make about the same output voltage to jump the air gap, the different shapes are for logistics imo. The input voltage to the low side of the coil is probably the same as your ignition voltage, 12.3 or whatever your system is running? I think that's the way it works? : )

If it were me at this point, or several points back I would have went brute force and put the volt meter away. Just kidding. Can you Jerry rig another coil [from dang near anything] into place and bypass your coil, and see if that lights the fire? Don't even have to run it through the plug. Just disconnect the wire under the boot on the top side of the plug and watch for spark when it's turning over? Old school, we would pull the plug and do the same thing and see if spark jumped across the plug electrode.

I already bought, tested, and installed a brand new functional coil. And new plug. Still doesn't fire. The problem isn't here

Quote: petro

If another coil doesn't ignite across the electodes +/-, than it probably isn't getting the juice from.....the brain? Or what tells this coil when to fire, there is no distributor anymore correct, everything's in that little brain afaik.

What are you trying to figure here, the resistance of porcelain? It should be close to infinite.

Proof of concept. Just seeing if I have understanding of all this.

No spark could be voltage drop as described above and tested via the procedure in your 2min video. But if it's not low power but instead NO power, as in my circuit is broken somewhere, isn't a continuity test using ohm resistance how you would find it? I mean, that's how I test for bunk parts. Coil should have 0.1 on the primary and ~5.0 on the secondary; if I test it and it's 0, I know the coil is fried. A wire should have 0. If I test it and there's any, I know the wire is cracked or connection is loose/dirty. So just as I tested a powered circuit for voltage to find voltage drop, wouldn't I do a similar test but with ohms on an unpowered circuit to look for breaks? Isn't that a continuity test and what one is used for?

I saw a few how-tos on how to test an ignition coil with a multimeter, with some suggestion as to what good values are.

I know you looked at this before, but it still sounds kinda kill-switchy to me.

Quote: Face

.... But if it's not low power but instead NO power, as in my circuit is broken somewhere, isn't a continuity test using ohm resistance how you would find it?

There is a possibility that we, all of us have different understandings of terms used. If I was looking for power or no power, I would be using a volt meter.

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I mean, that's how I test for bunk parts. Coil should have 0.1 on the primary and ~5.0 on the secondary; if I test it and it's 0, I know the coil is fried. A wire should have 0.

Are we trying to figure out the value of the insulation, where as if some of the electricity is leaking out, the voltage could be less at the far end? Other than the porcelain of the spark plug, for this case, and only using [guessing] no more than say 500 volts, all of the insulation on the wires should not fail to provide perfect insulation from fault. Any leakage I think, should be considered a total failure in a circuit, but not so much in a system. [we know that the starter battery can fluctuate a volt or so and still engage the starter, so that system has some built in forgiveness. Whereas the circuitry in the brain probably doesn't have appreciable forgiveness.]

Quote:

If I test it and there's any, I know the wire is cracked or connection is loose/dirty. So just as I tested a powered circuit for voltage to find voltage drop, wouldn't I do a similar test but with ohms on an unpowered circuit to look for breaks? Isn't that a continuity test and what one is used for?

If the wire is completely broken somewhere, or a switch or contact is open, you don't have continuity. If you are testing with an ohmeter, are you searching for known values or pass/fail?

I've read this about ten times and I'm getting mind ****ed.

An ohmeter can be used to test for continuity, obviously. But what a continuity tester is for is continuity. For a far out example: you can probably pull one car with a pickup truck using a taught chain and get continuity from the furthest bumpers. Or test to make sure there are no voids in a mile of cable. It probably looks the same, and mostly it is. But one is looking for resistance/insulation, the other as said, a continuous path for the flow of electrons.

You can take a mile of new urd cable ready to be buried underground and it will ring continuity from end to end, or should. But mid point somewhere there can be a nail driven into the wire from outside, which when buried will fault. But there is still continuity.

Quote: petroglyph

I've read this about ten times and I'm getting mind ****ed.

Damn, sorry for delay. Must've not hit "reply".

Pretty sure it's my fault as I was conflating practices. My experience forces continuity tests, as it's usually parts themselves that go bad and can't be tested while powered and plugged in. Since I'm so ignorant and that's my bread and butter, I always fall back to it as the solution. "If all you have is a hammer, everything looks like a nail", ya know? My fault lol.

Quote: Face

Damn, sorry for delay. Must've not hit "reply".

Pretty sure it's my fault as I was conflating practices. My experience forces continuity tests, as it's usually parts themselves that go bad and can't be tested while powered and plugged in.

That's a fine example of how I struggle about analogy's. You say "continuity" can't be tested while the circuit is energized. My retort is, there is more than one way to test "continuity". In an energized case example, if the circuit is energized and the voltage has made it to a certain point where the voltage can be observed, it has continuity as well.

Changing gears, who's familiar with thermal transfer coefficients? =D

It got too cold too fast and I need a work around for fish breeding. I have an idea, I just want to run it by some folks before wasting a couple day's labor...

So the idea was to use the outdoors as a free refrigerator, but to have control over it. My house and therefore the tank will be 70*. Out of doors will vary from 50* to -10*. My idea was to run a pump and plumb in a radiator. Pump tank water through a pipe, out of doors into an outdoor radiator, and then back through a pipe indoors and dump back into tank. Round and round we go.

Couldn't a regular ball valve be used as the temperature control?

It seems to me I'll have no problem cooling. The pump will cycle the entire tank in 2 min, and it's the high surface area of a radiator vs the surface area of my tank. Even using an old wheeler rad, the rad is gonna win out the transfer war. It seems, thinking it out, that the ball valve solution would work. If I blow it open, I could get the whole tank under 40 (it would seem) by having the whole tank exposed to winter every 2 min, whereas if I just trickle in squirts I could drop by decimal places. And if/when I get it stabilized in temp, it would / should only need checking on for swings in the weather. Little more flow when it warms, clamp it back when it's dead balls cold. That should work, right?

Hehe, typing this out, "working" is not my question. I know it will work. It's the water I'm unsure about. I don't know how it handles heat other than "confusingly". I def remember snorkeling / fishing and feeling 10*+ changes in one step, and I don't know why or how.

This doesn't have to be very accurate, but I need to keep my swings within ~+-10*. Assuming this setup and being checked once daily, do you think it's possible?

Quote: petroglyph

That's a fine example of how I struggle about analogy's. You say "continuity" can't be tested while the circuit is energized. My retort is, there is more than one way to test "continuity". In an energized case example, if the circuit is energized and the voltage has made it to a certain point where the voltage can be observed, it has continuity as well.

I dig, it's definitely a case of me being too stupid to speak properly.

But I'm a lot less stupid now. Thanks to all y'all =)