Instrument voltage regulator question
#1264966
07/09/12 09:48 PM
07/09/12 09:48 PM
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Joined: Jan 2003
Posts: 12,150 Benton, IL.
DaveRS23
OP
Special needs idiot
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OP
Special needs idiot
Joined: Jan 2003
Posts: 12,150
Benton, IL.
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I would like to change my failing dash voltage regulator in my 68 Dart for one of the transistor ones. Any one have a good source?
Thanks!
Master, again and still
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Re: Instrument voltage regulator question
[Re: DaveRS23]
#1264971
07/10/12 10:29 AM
07/10/12 10:29 AM
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Joined: Aug 2011
Posts: 3 fl
ic237
member
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member
Joined: Aug 2011
Posts: 3
fl
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Re: Instrument voltage regulator question
[Re: DaveRS23]
#1264972
07/10/12 10:29 AM
07/10/12 10:29 AM
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Joined: Dec 2007
Posts: 1,357 central Florida
VL21
pro stock
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pro stock
Joined: Dec 2007
Posts: 1,357
central Florida
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At first it does seem like a lot for something you cannot see and polish, and no one will ooh and awe over. Then I think about the fail safe modes for the gauges, the reliability, and the fact I will most likely never have to deal with the gauge problems again...seems more reasonable. I can't even go to a free cruise in without spending $20-30 on burgers and beverages... OK, so I like to eat.
It takes gasoline to interest me.
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Re: Instrument voltage regulator question
[Re: DaveRS23]
#1264973
07/10/12 12:31 PM
07/10/12 12:31 PM
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Joined: May 2008
Posts: 5,399 Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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You asked for a source, and the RTE regulator is the best solution. It is a direct plug in that looks correct, and it is a switching regulator, so it operates with low heat, quick gauge response, and protects the gauges from full voltage if the dash looses it's ground connection. It is quite a bit more complex than a linear voltage regulator.
On the otherhand, the linear voltage regulator is cheap and easy to build, but it generates quite a bit of heat and needs to be bolted to the regulator case (at a minimum - I will get to this later) to use the case body as a heat sink. Because of the bolt it won't look stock (like anyone is going to be looking under the dash anyway?) When I tested the gauges in my '69 Rally dash, each one used about 0.25 Amps at full scale, so the maximum current draw (Full tank of gas, 80+ PSI oil pressure, and the engine overheating) could possably pull 0.75 Amp from the regulator. The problem with the typical 7805 linear voltage regulator is that it will start to go into thermal shutdown around 0.5 Amp unless it has a good size heat sink. If you use a higher current rated 7805 (really just a 7805 regulator with a lower junction temperature so it dissipates heat better), and add a heat sink to the case then the linear regulator can handle the maximum current load. If you do not heat sink the regulator, and it starts to go into thermal shutdown, your gauges will not be accurate and will read lower than the true value. All that said, here is a list of the parts I used to build my linear regulator. Linear Regulator - UA7805CKC 5.0 Volt, 1.5A Regulator T0-220AB case, Digi-Key part # 296-1974-5-ND. Input side Capacitor - ECS-F1EE106K, 10ufd, 25 volt, Tantalum Capacitor, Digi-Key # P2049-ND. Output side Capacitor - ECS-F1CE105K, 1.0ufd, 16 volt, Tantalum Capacitor, Digi-Key # P2105-ND. Heat sink - 504222B0000, T0-220 case, 1.45", 10 Watt, Digi-Key # HS104-2-ND.
Dissasembly: carefully uncrimp the regulator case and remove the terminal board, then remove the mechanical regulator.
Assembly: Place the regulator inside the case, and the head sink on the outside to find the best location for drilling a mounting hole. drill the hole in the stock case. The Tantalum caps are small, so you can place them ontop the regulator and just wrap the cap leads around the regulator leads. solder wires and the caps to the regulator leads, the connect the wires to the stock input and output terminals, and the ground. Put some heat sink compound under the regulator and external heat sink, and bolt the regulator, case and heatsink together. Position/isolate the regulator leads so they don't touch the case body, then put the terminal board back in and re-crimp it. Where the ground connects to the case, solder it for a good ground connection. I used a large heatsink that I think the case would fit inside of, and then bent the leads out so the heat sink would fit close to the dash circuit board and not stick out the back.
I bench tested this setup at 0.8Amp and let it heat soak for almost a day, and it did not go into thermal shutdown.
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Re: Instrument voltage regulator question
[Re: RapidRobert]
#1264977
07/10/12 10:36 PM
07/10/12 10:36 PM
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Joined: Aug 2011
Posts: 3 fl
ic237
member
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member
Joined: Aug 2011
Posts: 3
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Quote:
Quote:
The third option is "switch mode regulators" thats what the Ebay one is. It works off of AC transformer priciples. It jas a fixed on off signal and then is buffed out with caps to a steady lower voltage. Without a ground it doesnt work and with an internal fault the chip goes high and the voltage goes low. Since its not linear it doesnt get hot like its counterpart. It will also provides overload protection as the linear versions.
You've convinced me! Where on eBay?
http://www.ebay.com/itm/280911702652?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1586.l2649
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