Vintage Lighting Old "Lighting Control" 2.4K dimmer voltage input

Techniq

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Hi!

I got old dimmer pieces in a high school and I want to control them with my Leprecon Lp-624 board that output analog 0-10V. My issue is that I think that those dimmers have analog input of 0-15V, but I don't really figure how can I get the answer. I'm afraid of burning electronic components if I put too much voltage. Those dimmers have also two trim pots, but I don't know their utility; could they possibly change the input rating at 0-10V instead of 0-15V?

I can post a picture if you want.

Thanks,

Pier-Luc
 
Hi!

I got old dimmer pieces in a high school and I want to control them with my Leprecon Lp-624 board that output analog 0-10V. My issue is that I think that those dimmers have analog input of 0-15V, but I don't really figure how can I get the answer. I'm afraid of burning electronic components if I put too much voltage. Those dimmers have also two trim pots, but I don't know their utility; could they possibly change the input rating at 0-10V instead of 0-15V?

I can post a picture if you want.

Thanks,

Pier-Luc

If you could provide the brand and model of the dimmers it would be of great help.

However from what I can get from your description you have an older type dimmer, with analog inputs. Most dimmers of this type are of the 0-10v variety, however from what you describe yours may be the rarer variety which were 0-15v. No matter what happens you can't burn out the electronics in the dimmers with your 624, as your 624 outputs 0-10v, so ether your 624 is a correct match to your dimmers or worst case senario your dimmers are 0-15v and you just wont be able to turn your dimmers onto full brightness. You would only be able to get up to something like 70% of their full output. The voltage is provided by the control board, not the dimmer itself so you don't need to worry about burning out any electronics. If you need a 0-15v output from your 624 you may need to invest in a DMX to Analog converter, I sure Doug Fleenor from Doug Fleenor Designs could build you a 0-15v converter from their 0-10v converters upon request.

The trim pots on the front of the dimmers are most likely to adjust the low side of the dimmer, if not properly adjusted your fixtures could glow because voltage is not completely cut off from the lamps. If any of your fixtures are ghosting, try adjusting the trim pots down.

If your dimmers are really that old then you should also check to make sure your dimmers are not the even MORE rare 2-7.6v variety. I'm sure Doug Fleenor could build you a converter for that too.
 
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Well, I don't know the specifics, but I'll just point out that if your board outputs 0-10v and you think the dimmers accept 0-15v, then there's no risk of "too much voltage." Hook it up and see if the lights runs 0-100 or 0-66.

The trim pots fine tune the relationship between the input control voltage and the output of the dimmers on the high and low end (essentially how the dimmers "interpret" the control voltage), so play with them and see what you get. I can't say whether they have enough adjustment to make it read 10v as full if it's expecting 15.
 
Thank you for answering so fast.

Well, what i did not explain to you is that I'm testing them with a variable power supply. This where the fear come from. On my voltmeter i get aproximately 90v when voltage input is 10. The dimmer model is PC 47B and is part of CL-R47J-6 fixed 12X2.4K dimmer pack.

Thanks,

Pier-Luc
 
Those model numbers do not show up anywhere on the internet as dimmers, what brand dimmers are they? TTI, Capitol, Strand, Century?

90v is 75% of 120v, which may be normal as most dimmers do not have a linear dimming curve, I would slowly raise your control voltage until your Input line voltage matches your dimmer output voltage, then see how many control volts you are outputting. It it's close or near 15v then your dimmer is most likely a 0-15v dimmer.
 
Thank you for answering so fast.

Well, what i did not explain to you is that I'm testing them with a variable power supply. This where the fear come from. On my voltmeter i get aproximately 90v when voltage input is 10. The dimmer model is PC 47B and is part of CL-R47J-6 fixed 12X2.4K dimmer pack.

Thanks,

Pier-Luc

Are you testing the dimmer's output voltage with a load on it? If not, your readings will not be accurate.
 
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You can only check with a load on, usually 100 watts is fine, one of the trimpots will be the low end trim, the other the high end trim, almost certainly you will be able to trim your desk to the dimmers.Try not to electrocute yourself in the process.
 
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Please make sure that you are using an RMS voltmeter otherwise your dimmer output readings will be incorrect.

David
 
I put the max trim to the maximum. How could I know if my volmeter is RMS?
Please take the time to read the referenced website below at the bottom.
If you don't have the paperwork on the meter still in your possession, try looking your exact model up on-line. The info on True RMS/ not True RMS should be there. If not I'd be suspecting it is NOT True RMS. My guess is the MSRP for true RMS meters is around $100 or more, but prices may be lower. So if it was inexpensive it may not be true RMS. Make sure it is a "True RMS" rating.
The following may not apply to you, but just in case:

Also, I feel, Category rating is important if your using the meter to check High Voltage lines. I'm not sure if 120V is as crucial as 480V and up for protection of the meters from high voltage transients. Others here will know...

Excerpt from Broadcast Engineering website:

Rating a meter by both category and voltage can be confusing, so here’s an explanation. If you ever work on power circuits then you need at least a CAT II or CAT III rated meter. Use only a meter with the proper category and an associated voltage rating, such as CAT III-600V or CAT III-1000V, marked on the front of the meter.

Old meters were rated with steady-state voltage withstand levels. So, in that sense, a 1000V-rated meter would be safer than a 750V-rated meter. But in today’s rating system that thinking only applies to meters in the same category. This means that a CAT III-1000V meter has better protection than a CAT III-600V meter. However, a CAT II-1000V meter is NOT “safer” than a CAT III-600V meter. Here’s why.

Under UL specifications, a CAT III-600V meter must pass a test against a transient with much more energy than the CAT II-1000V meter. A CAT III-600V will be tested with a transient, having the same peak voltage, but one that has one-sixth the test source impedance and therefore six times the current of the CAT II-1000V meter! Be sure you understand this key difference when selecting voltmeters.

A final meter purchase caveat. In addition to selecting voltmeters by category and voltage, look for certification by an independent testing lab, such as UL or CSA (Canadian Standards Association). Such certified meters have actually passed the mandated tests. Don’t settle for a meter that just says “designed to meet” or “conforms to IEC 61010.” Those statements are no substitute for independent testing. The adage, “It looks good on paper” is no substitute for real-world testing. Don’t let yourself become that one statistic where the meter “test” failed.

From Broadcast Engineering website: How safe is your voltmeter? | Brad on Broadcast
 
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If you don't have the paperwork on the meter still in your possession, try looking your exact model up on-line. The info on True RMS/ not True RMS should be there. If not I'd be suspecting it is NOT True RMS. My guess is the MSRP for true RMS meters is around $100 or more, but prices may be lower. So if it was inexpensive it may not be true RMS. Make sure it is a "True RMS" rating.
Ok thanks. I'll check. I have also acces to an oscilloscope so I can check the sinus wave. At 100%(10V), I should have a complete sinus wave at the output? How should I properly connect my dimmer with the oscilloscope?
 
Ok thanks. I'll check. I have also acces to an oscilloscope so I can check the sinus wave. At 100%(10V), I should have a complete sinus wave at the output? How should I properly connect my dimmer with the oscilloscope?

If it is a standard scope - don't do it. The ground lead of the probe is earth ground. Most if not all scope probes are not cat rated. Some scopes can't handle that high of a direct voltage either - especially in x1 mode. Use a Fluke ScopeMeter of a 120 series at least. You want a floating scope that is at least cat III 300vac dated. Just my advice though. I'm just not a fan of possible arc flash. Wear safety glasses at least.
 

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