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DJhandy
08-27-2007, 07:33 PM
I ordered a 115 volt primary, 12 volt secondary transformer. I received it and this is my problem: Has 2 wires for primary got that, has 2 red wires and one white wire on the secondary. When I connect to 115v and check the secondary Ground to white and check each red wire I have 7.5 volts out of each read wire. I need 12 volts, am I missing something? Why does it have 2 red wires? How do I get the 12 volts I need?

Reply appreciated

jimbo
08-27-2007, 07:51 PM
Whatever you are calling ground does not enter this equation.

Without actually seeing a diagram of that unit, I would suggest that the secondary is the two red wires. You would see about 15 volts ( open circuit). That is about normal to give you 12 volts under load. The white wire is the center tap, hence 1/2 the voltage from each red to the white.

DJhandy
08-27-2007, 08:03 PM
It has 2 black wires on the primary side. One white and two reds on the secondary side. If I connect meter: One leg to the white and one to either red I get 7.5 volts. How do I connect it to get 12 volts? I need it to connect to a govenor control box on a generator. I have two connections on the control box to connect the transformer too. The govenor control needs 12 volts to operate.

Thanks
DJ

hj
08-27-2007, 08:19 PM
is there any voltage between the two red wires?

Chris75
08-27-2007, 08:24 PM
I ordered a 115 volt primary, 12 volt secondary transformer. I received it and this is my problem: Has 2 wires for primary got that, has 2 red wires and one white wire on the secondary. When I connect to 115v and check the secondary Ground to white and check each red wire I have 7.5 volts out of each read wire. I need 12 volts, am I missing something? Why does it have 2 red wires? How do I get the 12 volts I need?

Reply appreciated


What brand and model so we can look it up online...

jadnashua
08-27-2007, 08:31 PM
Measure between the two red wires, tape off the white wire unless you have a need for half the voltage.

Furd
08-27-2007, 11:12 PM
I need it to connect to a govenor control box on a generator. I have two connections on the control box to connect the transformer too. The govenor control needs 12 volts to operate.

A transformer will output AC voltage. Are you sure that your application does not require DC?

DJhandy
08-28-2007, 07:24 AM
Yes I need 12 volt AC it is a replacement transformer. The old one had various voltages 6-9-12 I believe and the 12 was used. The model# 41FG300 is what was sent(no name or origin) as replacement and it states Pri: 115v Sec: 12.6 v
It supplies the signal to the governors board from the generator to control the engine speed. The wires from the transformer goes to a ground terminal and to signal in on governors board. The replacement transformer as stated previously has 2 black wires for primary, secondary has 2 red and one white wire. Power across both reds are 14-15 volts, from either red to white is 7.5 volts. I need 12 volts from single wire to connect to board and a ground wire to board. I've always used transformers that gave me the voltage I needed out of one wire. What do I need to accomplish what I seek?

Thanks for your help

HandyAndy
08-28-2007, 09:41 AM
first:
there is no such animal, you need two wires (paths), to make a complete circuit,

even a cars coil, (which is a transformer) is actually a two wire (paths) unit, the high voltage wire running to the spark plugs and the case of the coil which attaches to the bock of the motor and the spark plugs are also attached to the block of the motor, thus two wires even tho you only have (one visible wire) in other words there needs to be a complete circuit, which takes two avenues of path, (wires),

there is two wires,(paths) in the primary side of the transformer, and there are two or more paths, (depending on the taps) on the secondary side of the transformer), but each voltage needs a complete circuit to travel thus (for sake of better description) a path out of the transformer coil and one back in to coil. Now like in the cars coil the case of the coil is the other path (wire),

~~~~~~~~~~~~~~~~
two: apparently the transformer you have is different than the one that is in the generator, and you may need to go and get actual parts for that model


three: it sounds like to me you may be wise to take it to a an actual repair place that understands the workings of the generator and get fixed and checked out by some one who understands what is going on in the unit,

if you get it hooked up wrong you may end up costing your self much more than the price of the transformer,

jadnashua
08-28-2007, 09:50 AM
You might be able to attach one of the reds to the system ground and use the other lead as your hot. It doesn't matter which one.

DJhandy
08-28-2007, 02:34 PM
:) :) I contacted the manufacture Precision Governors (Chad a fine fellow)and jadnashua (moderator) you win the bragging rights and a big thank you.

One red goes to the + input and the other to the -terminal and wala 14.5 volts as needed.

I personally don't understand when u bench test an item and have 7.5 out of each lead and if you connect one leg to ground that 7.5v ends up in the positive leg giving 14 v. I've read and read about transformers. Can someone explain this in layman's terms??

Thanks to all for your help
DJ
Ready now Generator good to go it's a Diesel Isuzu 15KW

snafflekid
08-28-2007, 04:19 PM
One red wire to the white wire is a transformer tap for 7.5V

The white wire to the other red wire is another identical transformer tap for 7.5V

So, one red wire to the other red wire is like two taps in series, the voltages add and that makes 15V, or about 14.5 in your case.

jimbo
08-28-2007, 05:41 PM
There is no positive and negative on AC voltage , so you are mixing up the terms a little. I hope your device actually needed an AC voltage, and not 12 VDC

jadnashua
08-28-2007, 09:02 PM
The transformer secondary winding in your device has a tap in the middle (the white wire). While not an exact analogy, think of a variable resister with the wiper arm set exactly midpoint. If you run voltage through it, measuring from one end to the other, you get the full voltage; measure from one end to the middle, you get half.

this is the same idea as the power coming into your house...it is really 220vac, with a tap in the middle (your neutral), so you get 110 on each half referenced to the middle.

geniescience
08-29-2007, 08:59 AM
Diesel Isuzu 15KW
Isuzu 15KW VAC Diesel
gives me more search results than
Isuzu 15KW VDC Diesel
so without any more thinking,
I'll guess you have an AC thingie.

Transformers keep AC as AC
and DC, DC.

David

Rancher
08-29-2007, 09:04 AM
I personally don't understand when u bench test an item and have 7.5 out of each lead and if you connect one leg to ground that 7.5v ends up in the positive leg giving 14 v. I've read and read about transformers. Can someone explain this in layman's terms??AC transformers are spec'd at their full load current (or 80%, I forget) so if you bought a 1 Amp, 12 Volt CT (center tapped) transformer, the open circuit voltage could well be 15 volts as you have discovered, or 14 volts under load, or 12 volts under full load that the transformer was spec'd at.

Rancher

jwelectric
08-29-2007, 12:06 PM
Transformers keep AC as AC
and DC, DC.

David


nd DC, DC. ??????????

Have you learned how to transform DC?

Rancher
08-29-2007, 05:38 PM
nd DC, DC. ??????????

Have you learned how to transform DC?Sure you can transform DC, 12 Volts DC into one side of the transformer, 0 Volts DC out the other side.

Rancher

abikerboy
08-30-2007, 03:54 AM
nd DC, DC. ??????????

Have you learned how to transform DC?
Yea...it's called an "inverter"...lol!!! In the early days of electronics, it was called a "vibrating coil"... it was used to synthesise ac voltace out of a dc input by creating a chopped sign wave. Sorry guys, I just couldnt resist!

jwelectric
08-30-2007, 04:30 AM
Yea...it's called an "inverter"...lol!!! In the early days of electronics, it was called a "vibrating coil"... it was used to synthesise ac voltace out of a dc input by creating a chopped sign wave. Sorry guys, I just couldnt resist!

Does not an inverter work by reversing the polarity of the DC voltage applied to the transformer or in other words by alternating the polarity of the DC voltage.

jadnashua
08-30-2007, 06:32 AM
The better inverters make an actual nice, clean a/c signal. Mid-range ones make a stepped square wave, and the cheapest just make a noisey square wave. Most of them are nasty, though, and some things won't work well with the power they provide. They also tend to make a huge amount of electrical noise and rf. None that I"m familiar with reverse polarity to generate the wave, though.

geniescience
08-30-2007, 09:27 AM
The better inverters make an actual nice, clean a/c signal. Mid-range ones make a stepped square wave, and the cheapest just make a noisey square wave. Most of them are nasty, though, and some things won't work well with the power they provide. They also tend to make a huge amount of electrical noise and rf. None that I"m familiar with reverse polarity to generate the wave, though. off-topic, I'm wondering if a cheap invertor made for car lighter plugs can be used to charge a new Nokia cell phone without damage (to the Nokia).

David
p.s. also off-topic.
....Have you learned how to transform DC?Huh? clarity please, if you want to ask a direct question instead of addressing the subject as a subject matter expert. Or, just be a subject matter expert and share what you know, gently.

jadnashua
08-30-2007, 09:35 AM
For the cost of an inverter, (while maybe useful for various things), I think you'd be better off with their car charger cord. I'm lusting after their new N95...maybe when a carrier picks it up to subsidize (ATT listening?).

geniescience
08-30-2007, 09:43 AM
i have a 1st generation invertor but I'm wary about using it on a new Nokia. Unless I hear that new devices can handle a dirty wave signal.

david

jwelectric
08-30-2007, 12:47 PM
Have you learned how to transform DC?
p.s. also off-topic. Huh? clarity please, if you want to ask a direct question instead of addressing the subject as a subject matter expert. Or, just be a subject matter expert and share what you know, gently.

I did clarify the question here

Yea...it's called an "inverter"...lol!!! In the early days of electronics, it was called a "vibrating coil"... it was used to synthesise ac voltace out of a dc input by creating a chopped sign wave. Sorry guys, I just couldnt resist!

Does not an inverter work by reversing the polarity of the DC voltage applied to the transformer or in other words by alternating the polarity of the DC voltage.

abikerboy
08-30-2007, 10:35 PM
Does not an inverter work by reversing the polarity of the DC voltage applied to the transformer or in other words by alternating the polarity of the DC voltage.
Im not sure about the newer ones, or the ones made in recent years. The older ones would just "chop" the wave...you could actually measure a positive and a negative voltage at the 110 volt output. The old ones even up through the 1970's and I think some even up into the 80's (unsure about this though) used the vibrating coil, then the "chopped" 12 volt feed was sent through a step up transformer to increase the voltage to 110 volt. There was no positive or negative on the input. Both wires are black with alligator clips to attach them to a battery. The vibrating coil is not electronic, so it doesnt care which way you feed it. The voltage was never stable, and the frequency would vary quite a bit as you put more load on it. I have a very old one here...it belonged to my uncle that died in 1975 if that gives you any idea of its age...when you put power on it, it buzzes loudly from the vibrating coil, and it gets very hot even with no load on it. Its only rated for 75 watts, so all Ive ever used it for was to charge an electric razor, or to run a small lamp on it when camping out. Im not brave enough to plug anything electronic into it.

abikerboy
08-30-2007, 10:39 PM
i have a 1st generation invertor but I'm wary about using it on a new Nokia. Unless I hear that new devices can handle a dirty wave signal.

david
I wouldnt be brave enough to try it myself, though it actually might work. If it were me, Id just go to Wally world and buy the car cord that fits the phone for about $8 If you find out that it will or will not work, I would be curious to know.

jimbo
08-31-2007, 04:33 AM
An inverter takes the car's DC battery voltage and outputs an AC waveform. Most commonly sold inverters take the 12VDC and output 120VAC. We should stop talking about polarity with an AC wave because it is not relevant.

Your charging cube for the phone takes a regular household 120 VAC and makes a much lower voltage, DC, to charge the battery. Why would you start with a car battery, invert it up to 120 AC, then "wall wart" it back to low voltage DC???? Why not just plug the phone in directly with a car adapter?

geniescience
08-31-2007, 04:52 AM
it's a new phone, and the battery is so good they don't give you a car charger with it. Recently I did need to charge it, once, while in my car fro several hours. I later found an AC plug instead of using that old "toy" invertor. I had left the phone uncharged and out of service for a few hours.

((I have never used this inverter, although when I got it in 2004 I thought it would be good for a laptop, but then that just never happened either.))

Maybe one day someone who knows Nokia well might be able to say whether their phones can take a craggy AC wave.

david

geniescience
08-31-2007, 04:59 AM
ok, got it.

The inverter hopping back and forth from positive to negative is what you are talking about, and that is what i figured.

When you asked it to me, i thought it had something to do with my short statement about transformers keeping a current's wave pattern.

Later, it looks like the other meaning of reverse polarity got picked up, i.e. two reversed-polarity AC waves. Also not relevant now.

David

snafflekid
08-31-2007, 01:39 PM
A Nokia battery charger should be able to handle the crappiest waveforms you throw at it. The voltage is rectified and filtered then chopped again to achieve DC.

abikerboy
09-01-2007, 02:53 AM
An inverter takes the car's DC battery voltage and outputs an AC waveform. Most commonly sold inverters take the 12VDC and output 120VAC. We should stop talking about polarity with an AC wave because it is not relevant.

Your charging cube for the phone takes a regular household 120 VAC and makes a much lower voltage, DC, to charge the battery. Why would you start with a car battery, invert it up to 120 AC, then "wall mart" it back to low voltage DC???? Why not just plug the phone in directly with a car adapter?
AC relevance is very important...no gimmick here!!!! Early inverters relied on the "chopped" dc waveforms simply because the designers knew no better!!! READ YOUR INSTRUCTIONS for connecting early ac electronic "frequency sensative" devices! DUHHHHHHH!!!! A simple cell charger is a ac "frequency sensative" device! Yep...I'll admit to being a dummy when it comes to certain devices! Fried a "electronically" ballasted flourescent lamp in my camper with this inverter, yet magnetic ballasts survived!!! EARLY INVERTERS CHOPPED THE DC VOLTAGE AT A RATE OF 60 CYCLES PER SECOND....meaning the voltage was pullsed and blocked 60 TIMES A SECOND, thasnks to the diode and the SCR regulator!!!!! Newer inverters, as im told, REVERSE THIS CURRENT AT 60 CYLES PER SECOND, (yep...appears your right jadnusha) and even the newest devices do filter and round the wave....NOWHERE NEAR THE SAME!!!! Take an analog volt meter into the output of an older inverter...the neddle will vibrate towards the apositive READING....REVERSE THE LEADS, IT WILL VIBRATE TOWARDS THE ZERO, OR NEGATIVE SIDE!!! HOOK IT TO AC< AND IT WILL VIBRATE OR CYCLE IN BOTH DIRECTIONS EQUALLY!!! Explain this to me if "positive/negative doesnt matter with an inverter!!!! Tried this test today before even challenging this responce!!! Put the same analog meter into an ac outlet...meter set on dc...if your lucky, youll question the reading. Not lucky? Then buy a new meter!!! Smart enough to use an osscilliscope? Then you understand when u see the waveform!!! Not that smart? Back away, cause I WILL TELL YOU what I would connect to my own body, and what I would walk away from! If I die...my stupidity...not yours!!!

alternety
09-01-2007, 10:38 AM
The quality of inverter output varies significantly by price. Crappy ones give a series of stepped square waves with discrete increases in voltage until they get about where they are going and them back down. Lots of things hate this. Waveforms and voltmeter results would vary quite a bit.

A high end inverter can be found in solar systems and uninterpretable power supplies (not all of them are good). They can put out a pure sine wave as good as the outlet in your lining room. There is more than one way to do this but they essentially make the switching steps so small they become indistinguishable from a sine wave. If you look at one of these you would not see the funny results you get from a cheap one.

The ones made for use in cars used to use a "vibrator" (clean your minds up out there) which was just a buzzer with contacts driving a transformer. They were real bad. As noted in the post above above, some inverters just sort of replaced the buzzer with a solid state device.

abikerboy
09-03-2007, 03:24 AM
The ones made for use in cars used to use a "vibrator" (clean your minds up out there) which was just a buzzer with contacts driving a transformer. They were real bad. As noted in the post above above, some inverters just sort of replaced the buzzer with a solid state device.
Sorry guys...lol...I didnt mean the "DUHHH" in the earlier post above in a smart cocky way...after reading back, just sounded rude. It was really my duh (long story)... My appologies. It wasnt meant the way it read..