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analog, digital guages

Printed From: the12volt.com
Forum Name: Vehicle Wiring Information & File Requests
Forum Discription: Request Car Alarm, Car Stereo, Cruise Control, Remote Starter, Navigation, Mobile Video, and Other Vehicle Specific Wiring Info, Manuals, Tech Tips
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=132566
Printed Date: April 19, 2024 at 12:28 AM


Topic: analog, digital guages

Posted By: zister
Subject: analog, digital guages
Date Posted: November 03, 2012 at 9:30 PM

hi, looking for info on running analog & digital guages simultaneously.

I have a 92 s15 jimmy with a digital cluster & I have added a pillar guage pod with three analog guages one battery-oil pressure -& water temp. how do I hook up the analog without interupting the oem guages & vice versa

please any help would be appreciated!




Replies:

Posted By: howie ll
Date Posted: November 04, 2012 at 1:29 AM
You wire them in parallel and cross your fingers that the signal sources have enough current to swing both sets of gauges, all rather pointless (no pun intended) IMO.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: oldspark
Date Posted: November 04, 2012 at 4:04 AM
In short, no.

Analog gauges require senders/sensors matched to their requirements.
Normally these sensors are added - eg, oil galley & head water-jacket.
The voltmeter can simply be connected across the battery (thru an IGN +12V controlled relay if wanting it off when IGN is off).

"Digital gauge" sensors may be high-impedance types since the (analog to) digital circuitry merely requires a voltage.
They are usually unable to handle the current requirements of analog gauges even if they were to be matched, but the analog gauge would effect the digital reading (unless the analog meter replaced the dropping resistor for the digital sender, which IOW - forget it.


Besides, wouldn't you rather have redundant or two independent methods to measure the same parameter in case one gauge fails? (IE - as per Howard, "rather pointless" except when the superiority of an analog gauge is desired, though IMO the voltmeter is one of the few cases where a 3-digit gauge is the superior, and I understand why both are desirable for others like speed & RPM.)

If not and you want to use existing sensors, get an electronic analog meter or a voltmeter which is high-impedance and unlikely to effect the "digital" sensor output. Current-meter or "normal" analog gauges are unsuitable without an added conversion circuit - eg, a transconductance amplifier.




Posted By: howie ll
Date Posted: November 04, 2012 at 4:28 AM
Oops I read that the wrong way round, I thought the analogue gauges were original so I gave exactly the wrong reasons.
I withdraw my previous post and I'm now X 2 with Oldspark.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: oldspark
Date Posted: November 04, 2012 at 6:11 AM
Ah - thanks Howard.
Though you were not incorrect, I though it a somewhat strange reply given your knowledge - ie, though not incorrect, the chances of it being a reality are so slim.
(Even the chances of matching things as I described are slim, and that's after investigating or pulling apart; and substituting; and voiding warranties; and risking destruction; and & &...)


As to withdrawing posts - wow, did I just have a bad! (I won't mention "12V light flasher".)
These damned OldFart's that skim thru and think they know it all! ("it all" as in what's in the thread.)
They're as bad as injuneers!




Posted By: zister
Date Posted: November 04, 2012 at 11:02 AM
thanks for the info, I knew there was a signal shortage & I would need a different curcuitb to run the analog. but I didn't know what. Where or how do i make a transcunductance curcuit ? What is a transcunductant curcuit?




Posted By: oldspark
Date Posted: November 04, 2012 at 6:21 PM
Google it.

And - good luck!





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