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Old 07-17-2008, 10:44 AM   #1
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Voltage Stabilizer DIY


Please note that it is not my recommendation that you do this. I am simply showing how I assembled, soldered and installed my own. So if you try this project, it is your decision and do so of your own accord and assume full responsibility for your own actions. If you do complete this successfully you will gain, at a minimum, the knowledge of basic soldering and light fabrication skills. Please note, there is no guarantee on performance gains made here. I built and installed mine to help eliminate alternator whine and dash light dimming only. I was not looking at performance gains, I truly do not know if any were realized or not, as I have too many performance mods to really care. If I average 25 mpg (best average done by actual gas usage and calculator) then I am happy. Normally my average is around 23 mpg.

A tad bit of background info:

A voltage stabilizer is nothing more than a bank of capacitors used to stiffen a circuit. In this instance, the circuit is the automobiles electrical system. Stiffening a circuit is another way of saying reducing response time and controlling voltage/ amperage demands/ transitions, while also trimming signal (RF) noise. Capacitor banks are guaranteed to work. This is why they are used in home amplifiers, car amplifiers, car radios, linear power supplies, home PC power supplies, etc… Okay now to the actual stuff you want to read.


These are the tools I used, so understand, this can vary by availability and preference.
  • Soldering Iron – I use an adjustable iron, makes soldering different gauge wires easier
  • Small pair of dykes
  • Wire strippers - Able to strip down to 26 gauge wire
  • Alligator Clip stand – Looks like a paper weight w/ arms & gator clips attached
  • Vise – Optional (I used a suction mounted vise w/ soft jaws to hold the PCB’s)
  • Sponge – Dampened to clean solder from iron tip
  • Sandpaper – To clean & shape iron tip
  • Solder Sucker – Optional but recommended for oops’
  • Cordless drill
  • Screw drivers – Flat & Philips (for assembly purposes)
  • Crescent wrenches – 2 small ones (to tighten lock rings)
  • Print – A layout of all the items on the circuit board & their location (this is a must, it is worth the time & will make your life easier)
  • Razor Knife
  • Multi-meter w/ a continuity function


I tried to buy all my items from national chain stores so they woudl be available to most. I bought all my items from Autozone (A), Radio Shack (RS) or Home Depot(HD). The parts and numbers are as follows:

1. Blank Board – RS#: 276-1395
2. Blank Board – RS#: 276-149 (Not Needed)
3. Capacitor List:
a. (1) - Assorted Pack of Ceramic Disc Caps. RS#: 272-1388
b. (2) - 4.7uF Electrolytic Cap. RS#: 272-1024
c. (2) - 10uF Electrolytic Cap. RS#: 272-1025
d. (2) - 22uF Electrolytic Cap. RS#: 272-1026
e. (2) - 47uF Electrolytic Cap. RS#: 272-1027
f. (2) - 100uF Electrolytic Cap. RS#: 272-1028
g. (2) - 220uF Electrolytic Cap. RS#: 272-1029
h. (2) - 470uF Electrolytic Cap. RS#: 272-1030
i. (2) - 1000uF Electrolytic Cap. RS#: 272-1047 or 272-1032 or 272-1019
j. (2) - 4700uF Electrolytic Cap. RS#: 272-1022
4. Hook Up Wire – Red, Black & Green – RS #: 278-1221
5. Solder - Solid, Rosin Cored, Silver Bearing Solder –RS#: 64-017
6. PC Board Terminals – RS#: 276-1388
7. Project box – RS#: 270-1805
8. Flux Paste – RS#: 64-020
9. 20 amp Fuse Holder – RS#: 270-0016
10. 10mm High Stand Offs – RS#: 276- 1381 (Need to cut down to Ό”)
11. Green LED w/ Integrated Resistor – RS#: 276-271 (They also have these in Red & Amber)
12. Brass Nut, Bolts – HD# - Sorry, lost the wrappers. They are (2) Ό”x1” and (1) 10x32 x 1” fillister head machine screws
13. Water-tight Washers – HD#: Also lost this wrapper. They are in the specialty bins – Ό” & #10’s
14. 12v 30a Relay – A#: Dorman 84601


A. Start by un-wrapping everything and laying out the caps in order from highest value to lowest.
B. Now disassemble the project box (#7). You will not need the metal plate included in the package it is extra.
C. Measure the interior dimensions so you can cut your PCB (#1) to size. Measure carefully and it is better to make it a tad too big and trim it down then to make it too small and have it not fit right.
D. Cut you lower PCB to size first and leave at least a 1/8” gap around the sides. Use a razor knife and a steel rule to make your scores and then put the cut over a sharp edge and snap off the excess. Use sand-paper to smooth the edges down. You will notice the front half of the board will be un-supported, this is what the standoffs are for.
E. Now drill the rear mounting holes to match the ones that are already in the project box (#7). Drill very carefully as the board will chip & break easily. Then mount the board and measure for standoff height.
F. Trim the standoffs (#10) to match the height of the ones already formed into the box.
G. Mount the standoffs (#10) in the box so they will support the board and be out at the very edge to allow for max room on the board. Now mark the PCB and drill holes to match the standoffs (#10) locations.
H. Mount the lower board. Now measure & cut the vertical board. You will see vertical slots on the inside of the project box (#7). The board should fit snugly into these slots, but not so snug that it deforms the board.
I. Now remove both boards and set the vertical board aside for now.
J. Start laying out your Caps (#3) on the lower board. Start w/ the largest caps first and work your way down in size. Remember you have to mount one PC Board Terminal (#6) on this board. Mount these components so there is air space around each one. Also remember that all the caps are connected in parallel (pos. to pos. & neg. to neg.). Each component needs to be connected to the one in front of in this manner. So once they are all soldered you can run two wires from the last cap to the solder leads on the PC Board terminal. **NOTE** I laid my caps out so the leads of the last cap lined up with the leads for PC Board Terminal. This is very helpful later on.

K. Test fit the board into the box, (you will have to bend the leads over to do this). Now use a Sharpie to mark the exact mounting holes as you pull each component off the board. Once all locations are marked remount everything and bend the wires back over.

L. Now repeat step J, for the vertical board. You will notice that you have to mount these components higher on the board to clear the components on the lower board.
M. You will have to mount two (2) PC Board terminals (#6) on the vertical board. Remember one needs to face the lower board and one need to face the opposite way. These allow the two boards to be connected together and then tied into the relay.

N. Once everything has been test fit and the locations marked you are finally ready to solder.
O. Start with the lower board. Remove each component and lay it down in the exact layout that it is on the board.
P. Start at one corner of the board and tack each component into the copper rings. Work like a typewriter while doing this (go all the way across and then down a row). This keeps you from creating too small of an area to solder in. Once all of the components are soldered on to the top of the board it is time to make all the solders on the back.
Q. To make the lead connections easier mark all the positive leads on the back of the board w/ a small piece of tape or a red sharpie (Sharpie is better, not as hard as the tape).
R. Now start soldering positive lead to positive lead, then repeat in the same order w/ the negative leads. I bent my leads over to the nest cap, trimmed it to a Ό” overlap and then soldered it.

S. At the last cap or the one closest to the PC board terminal solder a lead or a jumper to the positive lead to one of the posts and the same with the negative. Use a multi-meter to do a continuity check of the completed circuit. Do this front the PC board terminal. Should show continuity (beep, light, etc… ).
T. Now you basically repeat all of this for the vertical board. The only difference is each end of the cap string will be attached to the 2 different PC board terminals. One PC board terminal connection at each end. Jumper wires will be used to connect the vertical board to the lower board later.

U. Once this is done test fit the boards to make sure they do not interfere with each other. Also cut two lengths of the hook-up wire to connect the two boards together via the PC board terminals. You can leave these connected
V. Now remove the boards and now it is time to install the brass bolts, green LED, fuse holder and relay. They will be installed in this order also.
W. Drill two holes for the Ό” bolts/ screws. These holes need to be very close to the actual bolt size.
X. Drill one hole for the 10-32 bolt/ screw. 10-32 = 0.201”; this is a #7 drill bit. You can use a 3/16” bit and thread the screw thru it, though.
Y. Measure and drill a hole on the adjacent side for the LED.
Z. Do the same for the Fuse holder. **NOTE** I know this is a large fuse holder, but I got this one because it will light up if the fuse is blown, makes diagnosis a real cinch.

This pictur shows the locations:

AA. Now do not tighten down the LED or fuse lock nuts yet, this will aid in hooking up wires.
BB. Decide which of the Ό” bolts is going to be the positive & mark it. Then cut three (3) pieces of, 8-12 gauge wire and one piece of 16-22 gauge wire; then install ring terminals on one end of each one. Mount the brass bolts, as follows, positive gets one 8-12 gauge, 10-32 bolt gets one 8-12 gauge, and the negative get the remaining two wires, (do not install the water proof washers yet). Now estimate the length of wire you are going to need for this and trim accordingly. Though check the next steps first, b/c I will explain what wire goes where.
CC. There are four (4) numbers on the back of the relay where the connecting posts are. These numbers correspond to what each leg does. Here are the #’s and their functions: 30 = Positive, 85 = Ground, 86 = Positive from switch, 87 = Positive to circuit to be controlled.

DD. So connect the wire from your positive bolt to one side of the fuse. Now connect a wire from the other side of the fuse to #30 on the relay. Next, you connect the 8-12 gauge wire from the Negative bolt (the one Ό” bolt you did not mark) to #85. Then you connect the wire from the 10-32 bolt to #86. Now #87 will be connected to the positive PC board terminal on the vertical board along w/ the positive from the green LED, (Cut and trim these wires now but do not install them yet). The 16-22 gauge wire from the negative bolt and the negative from the green LED will be connected to the negative PC board terminal on the vertical board, (Cut and trim these wires now but do not install them yet).
EE. Now with all the wires sized and ready you can install the water proof washers on the three (3) bolts. Remember each bolt gets two (2). One on the inside and one on the outside. It is best to install these with nothing else installed b/c the washers can be a pain to get on. Also remember you will need two (2) nuts for each bolt. The first locks the bolt down and the second will lock down the wires coming from the battery and your switch.
FF. You can now install the LED and Fuse holder and tighten down their lock nuts. Next hook up all your power and ground wires to the fuse and the relay.
GG. Now install your boards and connect you positive lead from your relay & LED to the vertical board.
HH. Next install your small ground wire from the bolt and the negative wire from the LED to the vertical board.

II. Now you can test your stabilizer with a pair of 9-volt batteries.
JJ. Hook the first battery to your main positive & negative bolts.
KK. Then hook the second batteries negative to the main negative bolt.
LL. Hook a wire to the second battery’s positive post and then touch it to the 10-32 bolt. You should hear the relay click and the green LED should light up. If this does not happen see the next step.

MM. Stop, drink a beer and calm down, while cursing under your breath, while blaming me.
NN. Now, go back and verify all of you connections. Then repeat steps II – LL.
OO. Yeah, it is all over… Now put the cover on and figure how & where to mount it. (I used automotive trim adhesive tape, lasts about a year or two.)
PP. Now you can install it, at your own risk of course. Big bolts are positive & negative to the battery. The little bolt is connected to the positive lead of anything powered on by the ignition, thus making the stabilizer only work while the key is on.

Post Script:

I hope I covered everything. If I have missed something please let me know. Also if something is unclear, please let me know and I will try and clarify the step and/or explain it to you.
**NOTE** The pretty window in mine was added as an after thought along with 2 LED’s to illuminate the Caps. Just a bit of bling, LOL. I did this w/ some really thin Plexiglas I had at the house, superglue (then permatex gasket goo, after super glue failed) and a 1-3/4” holesaw.
Just a quick note, I know there is a pack of resistors in the pic, but you do not need them. The resistor in the green LED will act as a bleed to discharge the caps when the ignition is turned off.

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