How can you combine 6 different ac voltages?

[Dawson]

I am building an alternator of my own. I have found that by putting 6 points around my magnets crates an insanely larger amount of electricity with very little force. I am producing around 20-25V out of each point totaling around 125-135V total ran off a tiny little airplane motor and 2 1" neodymium magnets. The problem is it's 6 different lines. I put them through their own full wave rectifiers and then combined those in series. This gets me up to around 95-100V dc but it doesn't combine the amperage for some reason so it's high volt but barely over the amperage I get out of one rectifier. Does anyone know a way to combine ac voltages without them fighting each other off? Or a way to combine DC voltages and combine their amperage as well?

 

[Julie.]

Let's say each gives 25V at 2A, this is 25x2 = 50W

Since you have 6 of them this totals 6 x 50W = 300W

If you combine them in series then 6 x 25V = 150V and the power would be the same 150V x 2A =300W

If you combine them in parallel the currents may add 6 x 2A = 12A and the power would be 12A x 25V =300W

You can't get more than is available no matter how you add them together.

In fact if you tried to add before conversion to dc then you could get considerably less.

 

[timhoward]

To combine AC voltages they would all need to be perfectly in phase which as far as I can tell would add considerable complexity to matters and unless you are spot on reduce the AC voltage you are starting with. Sticking to summing DC supplies is probably a better route, as above.

 

[Lucien Nunes]

nsanely larger amount of electricity with very little force. I am producing around 20-25V out of each point totaling around 125-135V total

A high voltage isn't a 'large amount of electricity'. When you walk across a nylon carpet in a dry room you can generate thousands of volts by friction with your shoe soles, but the amount of charge is so tiny there is hardly any electrical power available - it wouldn't light any kind of lamp.

The fundamental relationships of any generator are:
Voltage proportional to speed
Torque proportional to current

So it is quite reasonable to expect to be able to generate high voltages with little torque. Once you start drawing current from the generator, either the torque will increase to the point that the small motor can't drive it, or the voltage will collapse, or both. It's fun to experiment with things like this, I made little motors and generators when I was young and got a lot of satisfaction from them. But one must not expect to match the performance of a commercial unit with precision-engineered magnetic design. Maximum power transfer requires low reluctance magnetic circuits which in turn need highly optimised geometry and materials.

 

[Dawson]

A high voltage isn't a 'large amount of electricity'. When you walk across a nylon carpet in a dry room you can generate thousands of volts by friction with your shoe soles, but the amount of charge is so tiny there is hardly any electrical power available - it wouldn't light any kind of lamp.

The fundamental relationships of any generator are:
Voltage proportional to speed
Torque proportional to current

So it is quite reasonable to expect to be able to generate high voltages with little torque. Once you start drawing current from the generator, either the torque will increase to the point that the small motor can't drive it, or the voltage will collapse, or both. It's fun to experiment with things like this, I made little motors and generators when I was young and got a lot of satisfaction from them. But one must not expect to match the performance of a commercial unit with precision-engineered magnetic design. Maximum power transfer requires low reluctance magnetic circuits which in turn need highly optimised geometry and materials.

What do you know any way that I could turn voltage way down if I have had

A high voltage isn't a 'large amount of electricity'. When you walk across a nylon carpet in a dry room you can generate thousands of volts by friction with your shoe soles, but the amount of charge is so tiny there is hardly any electrical power available - it wouldn't light any kind of lamp.

The fundamental relationships of any generator are:
Voltage proportional to speed
Torque proportional to current

So it is quite reasonable to expect to be able to generate high voltages with little torque. Once you start drawing current from the generator, either the torque will increase to the point that the small motor can't drive it, or the voltage will collapse, or both. It's fun to experiment with things like this, I made little motors and generators when I was young and got a lot of satisfaction from them. But one must not expect to match the performance of a commercial unit with precision-engineered magnetic design. Maximum power transfer requires low reluctance magnetic circuits which in turn need highly optimised geometry and materials.

Do you know any way of turning it way down. Like 80kv to 240v. I made a tesla coil but it's unusable at that high rate. It also increases current of course which is what I need. Tesla knew how to make an oscillation without magnets and a motor which is incredible but the is too fast. Any ideas?

 

[Lucien Nunes]

The whole point of a Tesla coil is to make high-frequency, high voltages from low voltages. Why would you want to transform the output of a Tesla coil down? You are likely to end up with a very inefficient circuit that achieves nothing.

Returning to the original question which is more interesting. You can add any coils that are in phase, e.g. a pair of coils under which magnets pass simultaneously will produce waveforms in-phase so provided you connect them in series with the correct relative polarity, only one rectifier is needed for all. Coils or groups of coils that are not in phase need to be rectified and smoothed and then added in series as DC. Providing each rectifier with a smoother / reservoir capacitor (not just one across the final DC output) will give the sum of the peak coil voltages. Not doing so will give a lower voltage and higher losses as all the current flows through all the coils instead of the AC components of the rectified DC flowing through the (typically lower) ESR of the capacitors.

I have a small model generator for my Stuart model steam engine. Hidden inside the vintage style housing there is a stepper motor with 2-phase windings which makes quite an efficient generator delivering useful voltage at just a few hundred rpm. My coils are separately rectified and connected in parallel with a reservoir cap. It can light a few LEDs but the power available from the engine is very limited and half of it is lost in the generator and belt. One watt slows the engine significantly and a 4W car sidelamp bulb stalls it completely.

 

[Julie.]

The whole point of a Tesla coil is to make high-frequency, high voltages from low voltages. Why would you want to transform the output of a Tesla coil down? You are likely to end up with a very inefficient circuit that achieves nothing.

Returning to the original question which is more interesting. You can add any coils that are in phase, e.g. a pair of coils under which magnets pass simultaneously will produce waveforms in-phase so provided you connect them in series with the correct relative polarity, only one rectifier is needed for all. Coils or groups of coils that are not in phase need to be rectified and smoothed and then added in series as DC. Providing each rectifier with a smoother / reservoir capacitor (not just one across the final DC output) will give the sum of the peak coil voltages. Not doing so will give a lower voltage and higher losses as all the current flows through all the coils instead of the AC components of the rectified DC flowing through the (typically lower) ESR of the capacitors.

I have a small model generator for my Stuart model steam engine. Hidden inside the vintage style housing there is a stepper motor with 2-phase windings which makes quite an efficient generator delivering useful voltage at just a few hundred rpm. My coils are separately rectified and connected in parallel with a reservoir cap. It can light a few LEDs but the power available from the engine is very limited and half of it is lost in the generator and belt. One watt slows the engine significantly and a 4W car sidelamp bulb stalls it completely.

Which Stuart model?

Husband sold the TE, and either an 8 or 9, he has a half complete beam at the moment on the go.

 

[Lucien Nunes]

S50 mill engine. Built in 1980 when I was 8, from ready machined castings. I didn't have the resources and skills then to machine it myself. I do now but not enough hours in the day. My uncle builds models all the time, his speciality is hot air engines which have to be very finely made and fitted to run at all. But he also does steam and I/C. Anyway here is the S50 with 501 boiler. My dad wisely suggested that we opt for a boiler bigger than strictly necessary to steam the engine. He said 'Hopefully you'll get round to fitting a generator and then you will need all the steam you can get, and more.' He was completely correct, although as it took me 41 years to get round to it he did not live to see it generate.

Last steamed two weeks ago. It's a work in progress again, I am also making a feedwater heater and oil separator and considering a pressure-controlled gas servo valve.

 

[Julie.]

S50 mill engine. Built in 1980 when I was 8, from ready machined castings. I didn't have the resources and skills then to machine it myself. I do now but not enough hours in the day. My uncle builds models all the time, his speciality is hot air engines which have to be very finely made and fitted to run at all. But he also does steam and I/C. Anyway here is the S50 with 501 boiler. My dad wisely suggested that we opt for a boiler bigger than strictly necessary to steam the engine. He said 'Hopefully you'll get round to fitting a generator and then you will need all the steam you can get, and more.' He was completely correct, although as it took me 41 years to get round to it he did not live to see it generate.

Last steamed two weeks ago. It's a work in progress again, I am also making a feedwater heater and oil separator and considering a pressure-controlled gas servo valve.

Nice , very similar to the 9 my husband built - it was about a foot or so long from memory.

Hubby is into building these sort of things, no so much running them, so he's made a couple of locomotives ( 5" gauge) but then sells them to fund his next project after a short time. Never once seen him actually steam them around the track, but there are always willing drivers in the club who do, so they do get run.

We end up with some various static or loco model on the side for a short time unit it gets sold.

He has a few projects on at the moment, a Stuart beam (which is just a fill in project I think), a 7 1/2" Britannic, and early doors on another triple expansion (somewhat bigger and more involved than the Stuart TE).

He never concentrates 100% on the bigger models as they go on for years , so he always needs something else to complete in shorter time frames.

 

[telectrix]

Nice , very similar to the 9 my husband built - it was about a foot or so long from memory.

Hubby is into building these sort of things, no so much running them, so he's made a couple of locomotives ( 5" gauge) but then sells them to fund his next project after a short time. Never once seen him actually steam them around the track, but there are always willing drivers in the club who do, so they do get run.

We end up with some various static or loco model on the side for a short time unit it gets sold.

He has a few projects on at the moment, a Stuart beam (which is just a fill in project I think), a 7 1/2" Britannic, and early doors on another triple expansion (somewhat bigger and more involved than the Stuart TE).

He never concentrates 100% on the bigger models as they go on for years , so he always needs something else to complete in shorter time frames.

admit it then. youse married Fred Dibnah.

 

[Julie.]

admit it then. youse married Fred Dibnah.

Fred's dead.

Hubby just can't be bothered moving!!