6 Volt Ballast Resistor



The purpose of the resistor is to prolong the life of the distributor breaker points. If they are all the same, why are some marked 12v and 6v, different part numbers, etc. On the '46 Ford V-8 model, the ballast resistor is mounted on the interior of the car on the cowl, above the steering column, on a special rubber mount. The positive cable from the battery is connected to ground. About that time, they went to a resistor wire, and, 12v bypass system to improve starting in cold climates. I am finishing the wiring on my A-V8. Once the 12 volt coils and their additional energy potential got popular, fewer cars had ballast resistors. Look for cracked insulation, splices, bare spots, cuts, etc. read Old Car Electrical Systems Advantages of an Alternator. This is the coil that came standard on all [North American] BMW engines. The resistor limits the CURRENT going through the coil. 3 ohm ballast resistor. A 6 volt coil should definitely be run with the original resistor plus a second resistor in series. Converting a Ford 8N from a 6 volt to 12-volt electrical system may not be as difficult as you might expect. The question is, do I need a ballast resistor? This is the wiring diagram that I have been using as the engine came out of a 41 ford. Best modification that I did was to by-pass that terrible resistor wire burried deep in the wiring harness which will only become a source of problems in the future due to age and heat. The lamp is inserted in the circuit just like a tube filament. This will insure that only 6 volts reach the ignition points or they will burn prematurely. The voltage across the left resistor is 6 volts, and the voltage across the right resistor is 6 volts. 5 volt static. If converting from 6 to 12 volts and fitting this ignition system at the same time, the original ignition coils can be retained. Connect an insulated, AWG 20 copper stranded wire from the ballast resistor to the positive battery terminal or chassis. The ballast-resisted system utilises a 6 (commonly called the 'cold start' system) or 9-volt coil instead of the older style 12-volt item. you should then get a reading of around 1. Since it is still a six volt system, it will not have a ballast resistor. BALLAST RESISTOR. I know the "Ballast resistor" for my 1969 Dodge dart drops the voltage to the coil from 12 volts to 6 volts after ignition so one of those should work well. Our secure website and shopping cart allows you to shop with ease and be confident that your information is safe. com The ballast resistor is necessary only if your coil has less than 3 ohms as measured between the two primary terminals. We've got a wide rang of top-quality Jeep Cherokee Ballast Resistor of all the best brands in the industry at an affordable rate. Pick the best Ignition Resistor to suit your need at wholesale deals - We have an amazing selection of Ignition Resistor for sale from leading brands from Ebay. My question is, Can I just put a 12 volt coil on the car and dissconect the ballast wire? or should I try to get an external Ballast resistor from a different car?. With a fully staffed technical help department, helpful customer service reps, great product photos, helpful installation and repair videos, we are ready to help you restore your first antique tractor or your one hundredth. 4 ohm resistor. 6 V in and out across the primary terminals with no ballast. This bulb may also be obsolete and unavailable now. com - Online shopping from the largest selection of LED Lighting Products. coil ballast resistor, mounts on firewall, eal brand. Some make the assumption that there is a ballast resistor inside the coil but I don't think that is quite accurate. 5 ohnms its a ballast coil. Modern electronic switches such as this one Nology Ignition Module. I have similar arrangement, but with engine running the voltage to the coil is 11volts (14. 9 ohms fitted which gives me 6. If you have a starting solenoid for your starter, change it to 12 volts. In start the ballast is by-passed to deliver a full 12v for start. Slight oversimplification when cars changed from 6 volts to 12 the ignition wasn't a problem. Attach the Ignitor black wire to the negative coil terminal. 6 VOLT ELECTRICAL TIPS and TRICKS by "rumbleseat" I’ll use the term “VOM” to denote volt/ohm/amp/meter. 6 to 12 to 6 by Steve Delanty Owners of old cars and trucks that came with 6-volt electrical systems know what a drag 6 volts can be!Dim lights, slow cranking, weak spark, replacing generator brushes as a maintenance item, etc. ignition switch side of the ballast resistor. service manual for your vehicle to locate the ignition ballast resistor (or loom resistance wire). This is the coil that came standard on all [North American] BMW engines. 5v (as already stated) and is better at around 4. Series ballasts can only be wired in series according to the diagram on the ballast. Do not install a ballast resistor or relay on a Lucas 6 volt system. Less well understood is the fact that ballast resistors provide appropriate compensation within a circuit for external demands placed on that circuit. Design was based upon the information found in ‘The Ballast Tube Handbook’ by Jacobi and on the descriptive field of the R-390x part list: - Jacobi synthesizes data as: 8. Ballast resistor is part # FS-1008. Fluorescent lamps and fixtures using iron ballasts are basically pretty inert when unplugged. profhandy: Based on the info you supplied it sounds like you have it covered. 1 Volts as it empties. MCI SERVICE INFORMATION. I believe single should read 1. But, she's still smoking Car seems to run fine, but this really can't be right. 1 volt threshold voltage along with the 0. During the 6 to 12 volt transition period in the late 50s and early 60s, it was common for new cars to be equipped with 12 volt systems employing a 6 volt coil and ballast resistor. By working the formulas backwards, a 12-volt fan motor with the same 42 watt consumption (and same power output if the efficiency is the same) would have a resistance of 3. Filnor resistors are used for AC/DC motor acceleration, dynamic braking, ballast, load bank, neutral grounding resistors, harmonic filtering, and transit applications. Many 12 volt cars were manufactured with 6 volt coils. If your vehicle is not equipped with an ignition ballast resistor, install a Mallory Ignition Ballast Resistor Part No. A ballast coil should read around 1. 6 volt coils lasted a long time after. Replacement 12V coils, supposedly, are the same as a 6V coil, but incorporate an internal ballast resistor. 2 volt at the brown wire so i assume that the current draw from the choke heater, VR, alternator field, and ECU account for the voltage drop at the ballast). If it is a neg. The ballast resistor slightly reduces voltage at the points to increase their life and to help prevent "spark scatter. Slight oversimplification when cars changed from 6 volts to 12 the ignition wasn't a problem. Im thinking, because there is 12volt coils, to remove the ballast resistor as i think that is causing the car to cut out, due to it restricting the voltage to a weak 6 volts to feed two coils?. They used Delco resistors when IH switched to 12 volts. During the 6 to 12 volt transition period in the late 50s and early 60s, it was common for new cars to be equipped with 12 volt systems employing a 6 volt coil and ballast resistor. With 6 volts, P = 6 x 6, or 36 watts; with 12 volts, it's 12 x 12, or 144 WATTS!!! 4 x the original! That poor resistor is going to get DAMNED hot, and probably die quickly! This is the major problem running 6 volt devices from 12 volts. As the distributor spins the contact points touch and release with the timing of. Huge Selection of Vintage Ford Parts, Radiator Caps, Seats, and more. coil, ignition, 24-volt, for use with waterproof distributor. Mopar changed to the standard 6-volt coil mounted to the manifold when they began automotive production again after WWII in 1946. 74v If i take an ohm reading across the ballast resistor i'm getting 1. Here's a way to figure the sizes out as well as an alternate method: 6 To 12 Volt Conversion Guide. Replaced the broken but still working ballast with a 3 ohm resistor, had 12. This bulb may also be obsolete and unavailable now. Find Summit Racing® Ballast Resistors SUM-G5218 and get Free Shipping on Orders Over $99 at Summit Racing! These Summit® ballast resistors are perfect for protecting your points-style ignition system. Here's the scoop, it's a 6 volt coil! The resistor is there to drop the 12 volts (actually more like 13. If the total voltage is 20 volts, that resistor will drop 10 volts, or 50% of 20 volts. No matter what wattage resistor you have, it will see the same power. It looks like it is showing a ballast resistor (BR). It's the ballast resistor. These early Ballasted coils are known as 12 volt coils. I hope that makes sense?. Replacement 12V coils, supposedly, are the same as a 6V coil, but incorporate an internal ballast resistor. 12 Volt Coils For All Ballast Ignition Systems , sometimes known as 6 or 9 volt coils : Standard 1. Get the best deal for Electronic Ignition for 1955 Chevrolet Truck from the largest online selection at eBay. with the old points tuffnal cam heal coil would over heat,if wired through ballast with out wiring mod weak spark on cranking. 2 ohms or so ballast resistor. The black wire from the Pertonix igniter goes to the Ignition Switch. In this circuit the LED, a normal, old-fashioned indicator-type "non-high brightness" green LED was used, taking advantage of its 2. This was done because during cold weather the battery voltage can drop quite a lot. With the proper resistor, the coil voltage should be in the 6 to 8 volt range on a 12 volt system. I don't know if it came with a ballast resistor originally. 00 or very close to zero. If the voltage source is equal to the voltage drop of the LED, no resistor is required. When converting a 6 volt positive ground system to a 12 volt negative ground system, I add a resistor in line in front of the original 6v coil to reduce the voltage to the coil and distributor. 12 volt coil. When car starts the system voltage goes back to 12 volts so the ballast resistor or resistor wire is used to cut the voltage back to the 9 volts the coil was designed to operate. Electrical connections are shown above. The easy way is as I said earlier i. Arrow Highway, San Dimas, CA. You'll also need to replace any 6 volt bulbs with 12 volt. Powerflite - 2019-04-29 3:45 PM Yes, it makes sense when you consider the change from 6 volt to 12 volt. Get the best deal for Electronic Ignition for 1955 Chevrolet Truck from the largest online selection at eBay. When they converted to 12-volt in 1955, the coils were 12-volt and externally resisted. This gives a nice hot spark when the engine is cold. profhandy: Based on the info you supplied it sounds like you have it covered. The 12-volt motor would draw only 3. Your order may be eligible for Ship to Home, and shipping is free on all online orders of $35. Please Note: This article is meant solely as a guide to help you determine some of the systems that may need to be changed in order to convert from a 6V to 12V electrical system. 43243 ]] - Ballast Resistor. Browse your favorite brands affordable prices free shipping on many items. We provide complete technical assistance in order to meet your specifications. Tractor parts for your Ferguson and Massey Ferguson 6 Volt. When you hit the starter button/key, the coil is still seeing maximum current so produces a nice, big, fat, 12-volt induced spark to start the engine. Let the engine run for a few minutes. Get the best deal for Electronic Ignition for 1955 Chevrolet Truck from the largest online selection at eBay. High voltage output, oil filled for cool running. G) On a 6 volt positive ground model, remove the ignition switch (power) wire from the negative. Some are true 12 volt. How to Turn a 12-volt DC Into a 5- or 6-volt DC. BALLAST RESISTOR. Ballast resistors are high wattage, 20W and more, 0. We list day by day all N Ballast postings. It's the ballast resistor. 2 ohms or so ballast resistor. (See Figure B) 3. 5 Ohms Resistance //Push On Terminal // No Oil // Mount on any angle // For use with ballast resistor (not supplied). Shop with Confidence. I have heard some old-timers say the ballast resistor cuts the voltage by half, and so the points will continue to receive 6 volts as before. Also, do early. Yes, I actually feel it was the conversion from the 6 volt to the 12 volt that created the ballast resistor! Same ignition system with just the addition of the resistance!! Don't worry about being a non CC owner. Any grit sandpaper or even a small wire brush will work fine. Alternatively check the part number on the coil if you can find it. 6 VOLT ELECTRICAL TIPS and TRICKS by "rumbleseat" I'll use the term "VOM" to denote volt/ohm/amp/meter. We sell parts for Corvettes from 1953 through 2015 and are always on the cutting edge for new products that can add performance and style to your Corvette interior. com > Models > Jeep CJ Forum > 12v to 6v ballast resistor And I really don't know what heater he is actually running in the 76 that would use a 6 volt. What I have done here is to provide you with a sort of road map to perform the conversion. late cj-5/6 with v6 ohc-6-230 sw/pu. 12-volt power) and Negative goes to the distributor. The purpose of the resistor is to prolong the life of the distributor breaker points. 0 Ohms and are mostly in the circuit between the ignition switch and the positive side of the coil, coil minus goes to the points. -Prior to installing the negative battery terminal ensure there is a resistor integrated into the ignition system. Some where 6 volt. The resistor regulates the voltage, keeping it at 6 volts, allowing the original 6 volt coil to be used in a 12 electrical system. Once the 12 volt coils and their additional energy potential got popular, fewer cars had ballast resistors. Y-Block V8 (239, 272, 292, 312, 317, 341, 368) - Converting 6 Volt Distributor To 12 Volts - what does it take to use 6 volt distributor that came with this engine in 12 volt system?. Extensive array of ballast resistor at reasonable asking prices. 6 volt drop of an ordinary diode with a 5. 8 (note if i pull the Blue connector off of the ballast then i show 12. This can be solved by a voltage dropping resistor. Browse progressively our rundown of N Ballast deals from Ebay. First, we determine the device voltage, which is 3. 4 volts at 1/2 throttle. This is the coil that came standard on all [North American] BMW engines. If the motor has sat for sometime and starts hard, I have jumped them out with a wire just to get going as it gives a little stronger spark. STARTERS: The starter current draw on a Ford V-8 through 1948 is 550 amps (does not include V-8 60's). 5 volt, 3 volt, 5 volt, 6 volt, 7. Get the best deal for Electronic Ignition for 1955 Chevrolet Truck from the largest online selection at eBay. 12 volt coil resistor 1 #12336832 or NAPA ICR13 or standard Ignition VRC 604 Mount the ballast resistor to the firewall and. Just like you wouldn't use a 6 volt flashlight lamp to replace a burned out light in your house, you wouldn't use a 1/8 watt resistor when you should be using a 1/2 watt resistor. A 12 volt coil is required along with the correct ballast resistor. Try Prime All MACs Auto Parts 32-20898 Ballast Resistor - Needed When Converting Model B To 12 Volt. (These are fitted as. This gives a nice hot spark when the engine is cold. What purpose does that resistor serve anyway. The question is, do I need a ballast resistor? This is the wiring diagram that I have been using as the engine came out of a 41 ford. Slight oversimplification when cars changed from 6 volts to 12 the ignition wasn't a problem. Like mine did. Converting from 6 volts to 12 volts is pretty straight forward. External Resisted Ignition Coils have an internal resistance of 1. Your order may be eligible for Ship to Home, and shipping is free on all online orders of $35. If there is no voltage, there is a break in the circuit between the battery and the positive terminal. The engine can now be started. Negative - side of coil to points. Thanks, Mitch. Please know the resistance needed for your particular application — make sure that this is the correct ballast resistor for your needs before you buy. Browse progressively our rundown of N Ballast deals from Ebay. Attach the Ignitor red wire to the ignition side of resistance, or any 6-volt ignition power source. Dropping Resistor Calculator (The Calculator is at the bottom of the page if you want to skip ahead) If you want to try to run something off of a higher recommended voltage their are several ways to do it. 8 (note if i pull the Blue connector off of the ballast then i show 12. TEST before changing parts !. I have a 1986 Glastron with a 3. Attach one end of the first wire to the positive terminal on the power supply. The ballast resistor acts to increase the resistance in the primary coil circuit to get the current flow back to the more desirable 3 to 6 amp level. Those two situations are independent of. Some where 8-9 volt using a ballast resistor to cut the 12 volt to 9. Just cut the wire, add connectors and hook one. In start the ballast is by-passed to deliver a full 12v for start. Contrary to what that article states using a stock replacement 4-pin GM module DOES NOT elminate the need for a ballast resistor (the GM module and Mopar module are basically the same inside). I would like to be able to use a original 6 volt coil with the main coil wire facing towards the floor, and the electro lock from the dash-key to the top of the 6-v coil. My 1975 Norton Mk III uses 6 volt ignition coils. The most common reasons for an Ignitor not to work are low voltage or a bad ground (earth). If there is no voltage, there is a break in the circuit between the battery and the positive terminal. Pick the best Ignition Resistor to suit your need at wholesale deals - We have an amazing selection of Ignition Resistor for sale from leading brands from Ebay. is the reliability leader in the power resistor industry. AC Delco P/N U515. 5 ohms,add a 1. 5, spitfire 1975-1980, tr6 1973-this fits your 1978 mg mgb. Try Prime All MACs Auto Parts 32-20898 Ballast Resistor - Needed When Converting Model B To 12 Volt. This kit contains alternator bracket, instructions, reducers, horn relay, flasher, ballast resistor, D. 3 volts with tractor turned off and 6. As the current passes through the resistor the resistance increases substantially and reduces the voltage to the coil to about 6-8 Volts. 12 volt coil needs to see 3-4 ohms as measured between the two small primary terminals for best point life. For use with 6-volt and 12-volt automotive ignition systems only. Attach one end of the first wire to the positive terminal on the power supply. Fluorescent lamps and fixtures using iron ballasts are basically pretty inert when unplugged. On the '46 Ford V-8 model, the ballast resistor is mounted on the interior of the car on the cowl, above the steering column, on a special rubber mount. The 12 Volt systems were used 1957 and up. I get a lot of emails regarding this subject. home > ignition > ignition coils new and improved thundervolt iii coil is now 60,000 volts - must use with a ballast resistor. 12 volt conversion for a 54 Chevy. You will need a coil that is specifically designed to operate without a ballast like a GM HEI coil. 3V, coil voltage 3. (See Figure B) 2. I have similar arrangement, but with engine running the voltage to the coil is 11volts (14. When a 6 volt ignition system is converted to 12 volts either a 12 volt coil must be installed or a resistor installed in the circuit to reduce the coil voltage to 6 volts. I believe most 6 volt coils are rated for 8 volts. Huge Selection of Vintage Ford Parts, Radiator Caps, Seats, and more. Mopar changed to the standard 6-volt coil mounted to the manifold when they began automotive production again after WWII in 1946. This part is probably the easiest. Ballast resistor is part # FS-1008. Obviously, using a true 12volt coil will eliminate the need for a ballast resistor. 5 Ohm across the LT terminals. fatdsoto is VIP+ Member. Those two situations are independent of. When you engage the starter tumbler it by passes the ballast resistor and sends 12 volts straight to the eight volt coil to get good spark. Once running, the resistor is switched in place and the coil is actually getting less than 12volts. General Motors vehicles used the same 6-volt non-resistor ignition coil from 1923-'54. A non resistor coil has about 1. you should then get a reading of around 1. Obviously, using a true 12volt coil will eliminate the need for a ballast resistor. The ballast resistor is used to limit the current through the LED and to prevent that it burns. The reason for the 6 volt coils is they are wired together in a series circuit and as such they present a 12 volt load to the ignition module. I have a 1986 Glastron with a 3. Obviously that does not work with LEDs because they don’t behave like a linear resistor. The only time a ballast resistor is needed for the coil is if you have converted to a 12 vdc battery and 12vdc alternator and are still using the original 6 vdc coil. By the formula I found (Ohms x 2= volt drop) a 1. I am finishing the wiring on my A-V8. Frank at Holz. positive ground electronic magneto and a ballast resistor must be installed on the 12 volt Lucas system. The job of a resistor is to resist current flow through a circuit and it does this by dissipating the unwanted power as. 20 results for 12 volt to to 6 volt resistor Save 12 volt to to 6 volt resistor to get e-mail alerts and updates on your eBay Feed. But it was certainly included on the cars. A 6 volt ignition coil system generally operates with a ballast resistor and a contact breaker or point distributor. The ballast-resisted system utilises a 6 (commonly called the 'cold start' system) or 9-volt coil instead of the older style 12-volt item. 3 ohm coil and the 2. you should then get a reading of around 1. See N Ballast portrayal for description. Order ships free when this item is included and exceeds $99. howstuffinmycarworks. In order to increase the coil voltage at startup some ignition designs incorporate a "ballast" resistor. com: 12 volt to 6 volt resistor. If your tractor has regulated 6 volt generator you can simply replace the 6 volt regulator with a 12 volt regulator. Plug and harness. The 6 volt system didn't need it, and it was overlooked in '56 because those diagrams don't show it there either. This is a universal 12v coil that NEEDS a ballast resistor. This kit contains alternator bracket, instructions, reducers, horn relay, flasher, ballast resistor, D. 4 ohm resistor. It's my understanding the IC7 is ok to use without external resistor if it's for a 6 volt system. RatSport supply innovative & unique parts for vintage, classic, sports and kit cars. My question is, Can I just put a 12 volt coil on the car and dissconect the ballast wire? or should I try to get an external Ballast resistor from a different car?. It looks like it is showing a ballast resistor (BR). Either the ignition switch or the solenoid applied 12 volts to aid starting. A resister does not reduce voltage in an electrical circuit when a constant voltage is applied it lowers the current (amperage). This can be solved by a voltage dropping resistor. On the '46 Ford V-8 model, the ballast resistor is mounted on the interior of the car on the cowl, above the steering column, on a special rubber mount. Once the 12 volt coils and their additional energy potential got popular, fewer cars had ballast resistors. Resistor found in: Resistor Assembly, Universal 12-volt Voltage Resistor (2-terminal style), Internally Resisted 12 Volt Coil - Antique Tractor Blog, 6 Volt to 12 Volt Conversion FAQs - Antique Tractor Blog, Terminal Junction. If it's underrated then it will burn up. If your current 6 volt is a standard coil found on most domestic vehicles you will need a ballast resistor. A familiar and widely used example is the inductive ballast used in fluorescent lamps to limit the current through the tube, which would otherwise rise to a destructive level due to the negative differential resistance of the tube's voltage-current characteristic. The old resistor has no numbers and nor any way to check the ohms value. BALLAST RESISTOR. About that time, they went to a resistor wire, and, 12v bypass system to improve starting in cold climates. Please Note: This article is meant solely as a guide to help you determine some of the systems that may need to be changed in order to convert from a 6V to 12V electrical system. The wire running from the ignition switch to the coil, will need to be cut and a ballast resistor put in line. My car has a ballast resistor, I want to replace it. I have a 1986 Glastron with a 3. That resister changes the 12 volt current to 6 volts. with the old points tuffnal cam heal coil would over heat,if wired through ballast with out wiring mod weak spark on cranking. All vehicles with original equipment points ignition are factory equipped. FREE Shipping. Slight oversimplification when cars changed from 6 volts to 12 the ignition wasn't a problem. It's simply 6 + 6 = 12. In series circuit the 2 loads add together to equal 12 volts. Connect an insulated, AWG 20 copper stranded wire from the ballast resistor to the positive battery terminal or chassis. (See Figure B) 2. Filnor resistors are used for AC/DC motor acceleration, dynamic braking, ballast, load bank, neutral grounding resistors, harmonic filtering, and transit applications. I think i am OK for now. You can however use such coils provided you remove the ballast resister. The headache as to why there where 8-9 volt coils was that at one time the auto industry were making 6 volt autos with generators that pumped out 8-9 volts instead of amps to recharge the battery. A resister does not reduce voltage in an electrical circuit when a constant voltage is applied it lowers the current (amperage). My question is, what's really the difference between a 6 volt coil and a 12 volt coil? Why can't you put 12 volts through a 6 volt coil?. Showcasing Ballast Resistor for sale right now online. VOLVO AND SAAB These Swedish cars use an armored cable from the ignition switch to the coil. With a fully staffed technical help department, helpful customer service reps, great product photos, helpful installation and repair videos, we are ready to help you restore your first antique tractor or your one hundredth. 9 volt batteries are similiarily six 1. In this case, how the coil is powered to run the engine. In this case (during cranking) the resistor is by-passed to give the coil full (8 volt) power which it uses well but then when the starter switch is no longer "on. Showcasing Ballast Resistor for sale right now online. This is why you need a larger wattage resistor to handle the power that will go through it based on the resistance. The TR4 ignition system has no ballast resistor. These are the three equations of Ohms Law. I then connected the radio, which works great. Filnor, Inc. All About Ballast and Resistor Tubes Radio-Craft, January 1939 From the number of inquiries which have been I received recently, it is evident that there is considerable uncertainty among members of the radio industry regarding the function, purpose, and application of ballast tubes. It would start back up because during cranking, the ballast was bypassed. 20 results for 12 volt to 6 volt resistor Save 12 volt to 6 volt resistor to get e-mail alerts and updates on your eBay Feed. (the ballast resistor will be a somewhat pathway for the 12 volt ignition to travel throughie ignition feed to one side of ballast resistor wire from opposite end of ballast to positive side of coil. MSD Blaster II coils (. N Ballast Review. Any thought on reducing the 11v to less than 9? Thanks. 1984 - John M. This is the 12 Volt coil that will fit any model. The engine can now be started. In series circuit the 2 loads add together to equal 12 volts. Napa gave me an IC7 6-Volt replacement coil. This Video explains how the Ballast Resistor Works. We provide complete technical assistance in order to meet your specifications. The ballast resistor is used to increase a 6 volt coil OHM resistance from 1. 20 results for 12 volt to 6 volt resistor Save 12 volt to 6 volt resistor to get e-mail alerts and updates on your eBay Feed. A familiar and widely used example is the inductive ballast used in fluorescent lamps to limit the current through the tube, which would otherwise rise to a destructive level due to the negative differential resistance of the tube's voltage-current characteristic. It has the original 6 volt horn. It looks like it is showing a ballast resistor (BR). A: First up, the Classic Twin is a 12 volt ignition system designed to work with a 12 volt electrical system. Step 2: Test the resistance. Just installed the new ballast resistor! Battery voltage 6. 6 presents the human body model (HBM) value of nMOSFETs with and without body ballast resistors. It currently has a ballast resistor affixed to the firewall. If there is no voltage, there is a break in the circuit between the battery and the positive terminal. Cut two lengths of wire, and strip each wire of 1/2 inch of insulation at each end. The easy way is as I said earlier i. 74v If i take an ohm reading across the ballast resistor i'm getting 1. 1984 - John M.