6 Volt Cutout Question
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=115958
Printed Date: 18 Jul 2025 at 7:20am
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Topic: 6 Volt Cutout Question
Posted By: DennisA (IL)
Subject: 6 Volt Cutout Question
Date Posted: 09 Dec 2015 at 6:05pm
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This may be a dumb question but can a 6 volt cutout be used with a 12 volt system? ------------- Thanks & God Bless Dennis |
Replies:
Posted By: jaybmiller
Date Posted: 09 Dec 2015 at 7:00pm
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hmm had to think about this a bit...it would work but for how long,the coil will energize after the genny runs, so the relay would click in and charge the battery. the problem is if the coil will survive the 12V power to it. Gut feeling says sure ( aka overkill factor).. but any 12volt relay for say 'fog lights',rated for 20 amps would be a better choice.One of those small, black ice cube sized relays for $5. Another alternative would be to use a power diode,one good for 100PIV, 20A. Just wire it up right..if negative ground tractor ,cathode(band) goes towards the +ve of battery. I'm sure Steve of B&B will have some words of wisdom.... Jay ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: SteveM C/IL
Date Posted: 09 Dec 2015 at 8:45pm
| Jay,you make my head hurt.Glad someone understands this stuff. |
Posted By: steve(ill)
Date Posted: 09 Dec 2015 at 9:33pm
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cut out and light switch relay are old style to work with a basic 6 volt system... when you go to 12 volts, you eliminate BOTH and install a voltage regulator that does a MUCH better job of current and voltage control. ------------- Like them all, but love the "B"s. |
Posted By: DSeries4
Date Posted: 09 Dec 2015 at 9:36pm
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Exactly right Steve. Wanted to do that with my WD45 when we switched to 12 volts, but my local shop said it couldn't be done that way. The voltage regulator does make things pretty easy though.
------------- '49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '61 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080 |
Posted By: Gerald J.
Date Posted: 09 Dec 2015 at 10:28pm
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A big silicon diode should make a very fine cutout for a 6 volt 3 brush generator with no regulator. Back about 1968 I put a '67 VW 12 volt engine in my '64 6 volt VW. I couldn't install the 6 volt generator because the two generators were different sizes and the mount was very form fitting. I built a solid state regulator to regulate the 12 volt generator down to 7.2 volts and used a 35 amp silicon diode for the cutout. It worked very well. I had a voltmeter and ammeter, lab quality in that car. I had found that the original cutout let the generator draw about 10 amps reverse current at certain slow engine speeds before it disconnected. That reduced charging efficiency. The diode as cutout prevented that and the voltage regulation of the solid state regulator was much better than the original design, that seemed to at least double the battery life. The rub with a silicon diode as a cutout is that it will have a minimum of 0.6 volt and often 1 volt drop so the regulator regulating the armature voltage has to be raised by that much. The 3 brush original charging system with light switch and a simple cutout has practically no automation. It will easily overcharge the battery unless the operator detects the beginning of overcharging by the bubbling of the electrolyte and backs off the charge rate. In the long term that cuts battery life and in the short term it causes the battery to need water very often, like weekly or daily. The magnetic regulator of the next generation is better but not as good as a modern solid state regulator such as used in alternators because the newer regulator holds the charging voltage closer to what the battery needs. 14.2 volts is the optimum charging voltage if the battery is at 68 degrees F. That voltage can rise for higher and for lower temperatures. An ammeter will show that voltage is not too high when the charging current tapers to zero after some running time. A voltmeter may not be precise enough to show such details and for sure won't detect if the battery connections are open from corrosion. Gerald J. |
Posted By: Ted J
Date Posted: 10 Dec 2015 at 4:36am
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Gerald, you amaze me! Do you remember all this stuff, off the top of your head? I have a friend who is an electrical wizard, but he has to go look stuff up and get back to me. Do you do the same? You are a walking talking electrical engineer WIZARD! I enjoy reading all your dissertations and I learn a LOT!! MY PROBLEM is I can't retain any of it....  ------------- "Allis-Express" 19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17 |
Posted By: Steve in NJ
Date Posted: 10 Dec 2015 at 6:57am
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Upgrade to a Voltage Regulator as Steve mentioned and you'll be fine. Eliminate the 3 position switch and install a fused 12V Headlight switch to control Headlight/taillight functions. Keep it simple... Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: DougS
Date Posted: 10 Dec 2015 at 7:36am
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That old 6 volt/manual charge rate system did more to shorten battery life than anything. Just go with a 12 volt generator and regulator. It will pay for itself very quickly. |
Posted By: Gerald J.
Date Posted: 10 Dec 2015 at 10:41am
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I've been into electricity and electronics since grade school some 65 years ago. I got my first ham license at 13, the top grade one at 16. I went to college on a scholarship to study electrical engineering. I had a strong curiosity about electricity and I extracted knowledge from teachers that didn't have it. I went on to graduate school after working a while and graduated two more times. I hung out my shingle as a consulting electrical engineer for about 40 years designing a few products, designing and building a few custom products, investigating fires accused of electrical causes, investigating electrical injuries and deaths, investigating pig deaths from bad ventilation, and doing custom software development. As the result of those investigations I've been deposed about 200 times and testified in court as an expert witness about 75 times. I have a ruling in my files from the Iowa Appeals Court that says I am qualified to have and express an opinion in court. I took a model of one situation and operated it for the appeals court who rarely asks for witnesses. I am still hamming, up to microwaves, I'm writing articles each year for microwave and vhf conferences, and I still have the farm and the farm machinery that I take care of. My dad did lots of car engine work at home and I remember dodging hot chips with my bare feet as he reamed the ridge out of a 49 Willy Jeep wagon engine for its next rebuild. He built a garden tractor out of model A Ford parts and I held parts as he welded them together. I still have it. Need to get it running again. My folks raised a quarter acre of garden. So I have a diverse background and really love electricity and electronics. As an amateur musician, my major instruments have been piano, tuba, and double bass, though I have played trumpet, trombone, baritone, tympani, and drums in public and have learned bari sax and french horn too. I do have a large library at home but tractor electrics I learned about long ago as car electrics and don't have to look them up, but can if I forget. Gerald J. K0CQ |
Posted By: Dana(Iowa)
Date Posted: 10 Dec 2015 at 12:14pm
/\ /\ /\ Wow....I've lived a sheltered life compared to you! Amazing!  ------------- 1957 D-14 with loader 1947 Model C (restored) 1947 Model C (unrestored) SOLD! 1972 220 |
Posted By: FloydKS
Date Posted: 10 Dec 2015 at 12:30pm
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+1 on the amazing...
------------- Holding a grudge is like taking poison and expecting the other person to die |
Posted By: Coke-in-MN
Date Posted: 10 Dec 2015 at 12:30pm
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Could you use a zener diode for the voltage dump to control output voltage to a heat sink - ------------- Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something. "Challenges are what make life interesting; overcoming them is what makes life meaningful." |
Posted By: Gerald J.
Date Posted: 10 Dec 2015 at 1:11pm
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I do have a small farm, part of a bigger one I bought in 1989 and sold off the marsh land to the Iowa Natural Heritage Society helping them preserve the marsh. I farmed it for 19 years planning to build a house there but the prospect of a mall next door slowed my progress and I live a county north now and at 73 probably won't go build a house. I did build a liquid fertilizer side dresser and a three point sprayer for the farm. I'm relatively color blind for farm equipment, but I do have an AC plow that worked well until I went no till. I gathered farm equipment choices based on availability, function, and price. Fortunately SAE standards for three point and draw bar hitches make for relatively easy mixing of tractors and implements. AC snap couplers and IH two point hitches didn't make that mixing so easy. But then they wanted to be to sole vender for the entire system sold to a farmer. I did an involuntary army hitch during the Nam era and that affected my like of management so I kept my company mostly to a solo operation, when I hired help my productivity went negative because I "mother henned" them do death. Gerald J. |
Posted By: Gerald J.
Date Posted: 10 Dec 2015 at 1:13pm
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A zener diode with enough power rating might do that. Its easier to use a small zener diode to turn on a bipolar transistor for that. But what is the voltage dump application? Gerald J. |
Posted By: jaybmiller
Date Posted: 10 Dec 2015 at 7:58pm
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I'm thinking he wants to put a 6 volt zener in series with the cutout coil to run on 12 volts. Providing the Zener will handle the coil current it will work.Man that's real 'old school' and sadly I have an International booklet that shows that use of a zener !!! yeesh that's gotta be 45 years ago......................... sigh, great now I feel really old...probably should pull out the 2N107s and build something ?? Jay ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: Gerald J.
Date Posted: 11 Dec 2015 at 10:15am
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Actually needs to be a 7.1 volt zener, not 6 volts. While the nominal system voltages are 6 and 12 volts the actual charging voltage is 7.1 and 14.2 volts. The 2N107 was a really good germanium transistor compared to the slightly earlier CK722 that was noisy even at audio. It was also the first transistor to be sold for under a buck each. Germanium transistors were bad about leakage changing the operating point and being relatively unpredictable about the operating point. But with enough emitter circuit DC feed back they were predictable and I built a 2N107 audio oscillator once and heated the steel case hot enough to tin it with 60/40 solder. About the time the solder melted on the case it did stop oscillating, but it came back to work as it cooled. Way above its rated temperature range. I don't know if I could find my cache of 2N107 or CK722 in less than a couple months of searching but I believe I still have them somewhere. 2N2222 are much nicer transistors for most applications though the 2N3904 and 2N3906 are most popular today. Gerald J. |
Posted By: Brian Jasper co. Ia
Date Posted: 11 Dec 2015 at 1:05pm
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I would love to have an electronic regulator for a generator. How 'bout it Gerald and Jay... ------------- "Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford |
Posted By: Gerald J.
Date Posted: 11 Dec 2015 at 1:32pm
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I have built several for AC and for DC. My most recent one is riding on the Chinese locomotive on the Boone and Scenic Valley Railroad regulating the 50 volt generator to 32 volts because 50 volt quartz lamps became hard to find for the lights. It uses a TL431C IC for the reference and as an op amp, controlling the gate drive to a power MOSFET that controls the ground side of the field winding. I add a diode to protect the FET from inductive kick a couple resistors to limit currents, and one in parallel with the FET to cause the initial generator build. The MOSFET can't have a logic level gate, needs to have a higher threshold. Basically the last circuit in my 2010 paper: http://www.geraldj.networkiowa.com/papers/CSVHF2010/protection.pdf" rel="nofollow - http://www.geraldj.networkiowa.com/papers/CSVHF2010/protection.pdf with the lower MOSFET driving the field coil rather than the upper MOSFET and with a sturdy diode across the field coil to absorb inductive kick. Plus a 200 ohm or so resistor in parallel with the lower MOSFET to give some field current to cause the generator to build when started. I believe some of the automotive regulators sold in the car part stores for replacing old regulators are now solid state even though the package looks like a magnetic regulator. I'm not sure the car parts vendors want to admit them though. Today the solid state regulator can be so simple its cheaper to make than to use up the copper and steel of the classic regulator and has better regulation for better battery life. Gerald J. |
Posted By: Brian Jasper co. Ia
Date Posted: 11 Dec 2015 at 5:28pm
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I know it's tough to find an electro-mechanical regulator for the 1G Fords. It's enough of a problem that some of the reproduction parts places sell the original style covers. Grind off the rivets, a couple screws, and you have an original looking regulator with the improvements of electronic control. ------------- "Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford |