Instrument voltage regulator question

try this
less than half of rte
http://www.ebay.com/itm/280911702652?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1586.l2649

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.

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.

I'll just give another thumbs up to RT Engineerings version. I bought one off a member here at a great discount and would have thought it a bargain at full price. The peace of mind knowing my gauges aren't going to fry is worth it alone. The added bonus is it looks stock except when it's operating and the little LED in the back begins blinking to let you know things are a okay. Installation under dash is doable, but it's really a pain in the neck.

Whats nice about the rte unit is that it looks original and duplicates the pulses as they should have been in a perfect world. However, the do have that nasty little draw back. If yoi pay attention to their sequence of operation you will notice a flaw that could/will undermine the protection which its supposed to do. When you hit key on it goes into a full 12 volt sequence to warm up the gauges as the original did. But one thing the ofiginal did was retain heat. So in that cold morning where the car doesn't want to start and you are cranking away, you are effectively causing damage to your system. The original ivr would atleast be warm enough to start regulating. Rte doesn't know the difference and starts pumping away.when you troubleshoot over the phone its never the regulators fault, must be bad gauges or sendors... The linear regulators are nice too. They just two hours or so to get it in the old can if you are goinv for the nastalgic look, they to have their drawbavks. One is if they loose ground they will output the full battery voltage. Also if they fail, internal fault, they will also put out full juice.. 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.