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Resistor and Capacitor ID

RLM431 — Fri, 30 May 2025 00:41:54 GMT

Hello

New to the site. I’m no engineer and not an avid electronics enthusiast but I tinker with things. I can research and typically find an answer but I’m having a little difficulty with 2 capacitors and 1 resistor. They’re from an old marine tachometer I’m trying to bring back to life. I’m looking for some help identifying them and suitable replacements. I have attached a couple of pictures.

Any help is very much appreciated.

- RL

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RE: Resistor and Capacitor ID

kmikemoo — Fri, 30 May 2025 13:54:00 GMT

anniel747 I vaguely remember some odd notation in older service manuals, but on the vintage radio equipment and OLD Basler voltage regulators that I've worked on, they're all rated in microfarads - MFD. It's probably because there wasn't an ASCII symbol for mu, µ, back then.

RE: Resistor and Capacitor ID

anniel747 — Fri, 30 May 2025 12:13:45 GMT

[deleted]

RE: Resistor and Capacitor ID

RLM431 — Fri, 30 May 2025 02:26:04 GMT

Kmikemoo, I’m trying to reply on my phone so not sure how to tag you but, thank you! Yeah, that resistor is toasted, I can identify the last 3 bands but not the first. I’ve been scouring the www for a schematic but nothing comes up for the darn thing. If I had found oIt’s a 70’s omc accessories 2 wire tach, just signal input and ground. It was made by gale products and model # is 121614. If I do find one it will be a lot easier.

RE: Resistor and Capacitor ID

kmikemoo — Fri, 30 May 2025 01:00:26 GMT

For Picture 1, you'd be better off searching for a schematic for that tach. It's fried beyond recognition for me.

Picture 2: https://www.newark.com/cornell-dubilier/942c20p15k-f/film-capacitor-pp-0-15uf-2000v/dp/66K5447

Picture 3: https://www.newark.com/cornell-dubilier/940c20p1k-f/capacitor-polypropylene-pp-film/dp/66K5379

Any help on the following low pass filter scenario would be very much appreciated.

k.morrow — Thu, 24 Oct 2024 16:25:11 GMT

Objective: To build a shielded cable with a passive low pass filter to be used for connecting the ground connection of a typical US 120V socket or from an earth ground rod to a bed sheet with silver threads in it for grounding or earthing purposes. The purpose is for the filter to eliminate any/all AC noise from going up the shielded cable and getting to the bed sheet.
For testing possible filter configurations I have a Fluke 179 True RMS multimeter and an old Hitachi V-152F-15MHz Oscope and a BK 3011B - 2 MHz Function generator.

My thoughts are to use a single resistor with an electrolytic capacitor so when measured with the multimeter in one direction I would measure the resistor value and in the other direction I would measure an infinite impedance.

I have explored several online low pass filter calculators:
www.redcrab-software.com/.../RC-Low-Pass-Filter
sim.okawa-denshi.jp/.../CRlowkeisan.htm
learningaboutelectronics.com/.../Low-pass-filter-calculator.php
markimicrowave.com/.../

I have a few questions:
1. Do I make the filter with a cutoff frequency of 60Hz or something very low like 1Hz or less?
2. Is an RC filter best or use an RLC or some other config?
3. Could the filter be better with a 2nd order (or 3rd, or 4th ...?).
4. For the filter connected to a shielded cable, are surface mount components better to use than leaded components?

Thank You!!

RE: Any help on the following low pass filter scenario would be very much appreciated.

James123 — Sat, 02 Nov 2024 09:05:32 GMT

Setting the cutoff frequency of the filter to 60Hz should be sufficient, as this is the standard frequency for alternating current. If only simple low-pass filtering is needed, an RC filter is enough; it is the simplest passive low-pass filter.

RE: Any help on the following low pass filter scenario would be very much appreciated.

michaelkellett — Fri, 25 Oct 2024 08:02:12 GMT

Strewth !

Thanks kmikemoo

Science:

As far as RF is concerned it will make little difference to the electric field just above the "silver" sheet if you connect the ground wire or not.

Why - because the inductance of the wire and the mains wiring in the house will have a high impedance to ground at RF.

The usual analogy in EMC testing is that grounding a large conducting structure with a wire longer than couple of inches is like trying to push an elephant with a piece of wet string.

Nonsense: (you were warned !!!)

https://www.youtube.com/@groundedwellness4359

RE: Any help on the following low pass filter scenario would be very much appreciated.

dougw — Fri, 25 Oct 2024 00:29:46 GMT

The resistor is all you need for ESD. That capacitor is big enough to give you a jolt if you have built up static electricity. The cap may have bled off to ground but if you are charged up it will allow rapid current inrush as you touch the sheet and the cap charges up to your potential (possibly causing a spark)

Other notes:

Ground by definition has no AC on it, but of course it depends on where you measure from and if there is current flowing in the ground causing IR voltages.

As mentioned a polarized cap isn't ideal for a situation where it is not clear what voltage polarity will be applied.

The shield in the diagram is just ground - no part of it is floating. I'm not clear what the "floating" lead is connected to off in the direction of the sheet, but if it is the conductive sheet, then the rest of the circuit is shorted out and not doing anything.

If you are worried about ground faults causing a shock, maybe consider a ground fault interrupter (GFI).

RE: Any help on the following low pass filter scenario would be very much appreciated.

anniel747 — Thu, 24 Oct 2024 23:31:57 GMT

Why the polarised capacitor?

RE: Any help on the following low pass filter scenario would be very much appreciated.

anniel747 — Thu, 24 Oct 2024 23:29:49 GMT

How did you measure that noise?

RE: Any help on the following low pass filter scenario would be very much appreciated.

k.morrow — Thu, 24 Oct 2024 21:56:05 GMT

It is the same concept as hooking up an ESD mat except I'm trying to filter any and all noise on the cable from the wall outlet ground to the ESD mat.

RE: Any help on the following low pass filter scenario would be very much appreciated.

k.morrow — Thu, 24 Oct 2024 21:49:54 GMT

I am trying to eliminate any AC noise that is on the house ground from going up the shielded cable to the conductive bed sheet.

I have attached a picture of what I want to do.community.element14.com/.../Low_5F00_Pass_5F00_filter_5F00_concept.pdf

RE: Any help on the following low pass filter scenario would be very much appreciated.

battlecoder — Thu, 24 Oct 2024 20:12:49 GMT

+1 to this. I'm absolutely not an expert, but if the cable is connected to ground, all "radiation" it might be subjected to, will be grounded just like any RF emissions picked up by the sheet itself. The cable won't be any different from the sheet, in a way, so I'm not sure any "shielding" or filtering is required at all.

RE: Any help on the following low pass filter scenario would be very much appreciated.

kmikemoo — Thu, 24 Oct 2024 19:52:03 GMT

michaelkellett This is actually a thing. https://www.amazon.com/Grounding-Silver-Conductive-Earthing-Better/dp/B0CJJ8G1M1

RE: Any help on the following low pass filter scenario would be very much appreciated.

dougw — Thu, 24 Oct 2024 18:34:27 GMT

If the only connection is ground, what are you filtering with respect to? I'm not sure you can do better than a direct connection to ground to minimize capacitive, inductive or RF coupling to the sheet..

Is ESD of concern? (because that would have a different solution)

If there is no other specific ground reference, an in-line inductor might do something to minimize AC with respect to the natural ambient ground.

RE: Any help on the following low pass filter scenario would be very much appreciated.

michaelkellett — Thu, 24 Oct 2024 17:13:58 GMT

Please also explain "bed sheet" is this a sheet on a bed for sleeping - if so there could be problems with safety.

RE: Any help on the following low pass filter scenario would be very much appreciated.

anniel747 — Thu, 24 Oct 2024 16:33:37 GMT

A schematic of your intended connections please.

My photocell for outdoor lighting does not light up if power went during off the day

cksimkoza4 — Thu, 11 Jan 2024 23:42:10 GMT

and it comes during the night.what could be the problem

[View:https://drive.google.com/file/d/1mj7He4cGg-EBredtfb1ftzhbO1iRuJQV/view?usp=sharing:640:50][View:https://drive.google.com/file/d/1WmcJAjJPwMtt1xPhVvz6tuBRzhClLTFc/view?usp=sharing:640:50]

RE: My photocell for outdoor lighting does not light up if power went during off the day and it comes during the night.what could be the problem

DAB — Sat, 13 Jan 2024 19:52:00 GMT

I am not sure about your unit, but on my outside lights, I can "set the state" of mine by turning the power on and off. If I just toggle the switch, the light comes on and stays on.

If I turn it off for 30 seconds and then turn it on, the light will come on for five minutes and then automatically go out.

RE: My photocell for outdoor lighting does not light up if power went during off the day and it comes during the night.what could be the problem

Jan Cumps — Sat, 13 Jan 2024 12:15:06 GMT

What I think happens:

It needs a transition from light to dark, to trigger the relay.

When it's switched on at night, when it's already dark, this condition doesn't happen. It's dark and it stays dark. And the relay will not switch.

RE: My photocell for outdoor lighting does not light up if power went during off the day and it comes during the night.what could be the problem

Jan Cumps — Sat, 13 Jan 2024 11:27:19 GMT

This one seems to have no intelligence.

STA-T90 relay,
CDS light cell
trim pot
3 electrolytes
what I think is a polypropylene cap

RE: My photocell for outdoor lighting does not light up if power went during off the day and it comes during the night.what could be the problem

robogary — Sat, 13 Jan 2024 01:26:19 GMT

You need to read the datasheet for the light. Some of these lights are programmable, and the "keyboard" is the light switch.

RE: My photocell for outdoor lighting does not light up if power went during off the day and it comes during the night.what could be the problem

kmikemoo — Fri, 12 Jan 2024 16:33:43 GMT

cksimkoza4 Thank you. I understand much better now. I do not have a solution. I do have occupancy sensors that behave similarly when the returning mains power is from my battery inverter. They only reset when powered by utility power. This validates JWx's suggestion that it could be an edge triggering issue - at least in my mind. If you were able to reset the mains power to the circuit after the lights failed to come back on, do they behave correctly? Power quality is terrible as mains power returns - with everything trying to restart.

The other crazy idea is if your photosensor has analog potentiometers. Sometimes these items get oxidized. Note the position of the pointer. Turn left, right, left right, and back to the original position. While simple, I have corrected many sensing problems this way.

RE: My photocell for outdoor lighting does not light up if power went during off the day and it comes during the night.what could be the problem

JWx — Fri, 12 Jan 2024 14:57:11 GMT

maybe lighting conditions during the night has changed? let's suppose that this sensor has three states "definitely day", "intermediate state" and "definitely night", and in "intermediate state" it's behavior depends on previous state. In this case, when some times ago night was darker than now, it correctly interpreted it every time as "definitely night", but now it is fitting into "intermediate state", which is working correctly when it "sees" difference from day to this "intermediate state" but not when it powers-up in this state? Maybe there is some sensitivity potentiometer that can be tuned (after remembering current position for easy return if it doesn't work)?