Fulgurex - Diodes

"Ian J." a écrit dans le message de news: snipped-for-privacy@individual.net...

motors. I use a SPDT switch and 2 diodes. The AC power connected to the center of the Swich; the diodes conneted to the external connectors: one with the anode facing the connector the other one the cothode.Then the other sides of the diodes connected toghteher. and than to the Fulgurex motor; outlet of motor to the AC return. With this setup when throwing the switch to one side only ojne half of the AC is going (or coming) from the motor which will rotate CW or CCW depending which way you throw the switch. I dont remember the AC voltage I am using but I think 16 AC will do it (Try on one motor first if it smells too much or smoke then lower the voltage or use it as a toaster!) Regards Jacques

Don't think you were the original reply, but thanks for replying now. I am aware of the wiring set up, but I am not a wiz with electrics or electronics, so I need to know the specification for the diodes, as there seem to be so many things to consider with them....

Ian J.

Ian,

The 1N4000 series diodes are fine at 1A rating. (The running current being down in the low 100's mA). The last digit gives the peak inverse voltage rating. So:-

Fulgarex motors take around 400mA when starting.

Len wrote:

I would imagine the surge current and back current would be several times higher than that on switch on/off, though. 1A should be enough, all the same.

Whilst using the diodes that the other posters (In4000 series) will work to convert AC to DC you could use a bridge recitifier instead W005, W01, W02, or W04 this is a component which basicly contains 4 individual diodes wired up correctly. I suspect that that this might be easier for you to use. Both solutions will work for either of the voltages. These are available from maplin or squires.

What could be a problem that hasn't been addressed by the original posters is that you say you need 16V converting to 8V or 12V to 6V how critical are the lower voltage in each pair? The voltage drop across either the individual diodes or a bridge package will not reduce each by 50%. If the voltage is critical then an some additional components may be required.

Many thanks to all posters so far.

I think for the point motors, it will be easiest to stick with the diodes themselves, as there are 22 turnouts...(!)

As for voltages, I was (in my electrical ignorance) presuming that by taking half the wave of the AC I'd end up with half the DC (!). If not, then I will need resistors in place to take out the remainder of the voltage I don't need (for point motors I want them at between 8V and 10V)

Ian J.

I use 1N4001, but any diode rated 1 A will do. My AC power is 12 volts: motor makes enough noise with that ! BTW I use an other setup which gives me at the same time a led indicator on the control panel just by adding 2 leds an a 470 ohm resistor. If interested send a e-mail (remove nospamno) regards jacques

My experience has been that taking a 12v AC supply, splitting it with a pair of 1N4000 diodes, and operating the point motors on half-wave DC is absolutely fine. What's the concern about the specific voltage? Some of my older point motors are fulgurex and these have a small pot in series with the one of the feeds, so the speed of the point motor can be reduced. Sadly it doesn't reduce the noise of these machines though...

John

My experience has been that taking a 12v AC supply, splitting it with a pair of 1N4000 diodes, and operating the point motors on half-wave DC is absolutely fine. What's the concern about the specific voltage? Some of my older point motors are fulgurex and these have a small pot in series with the one of the feeds, so the speed of the point motor can be reduced. Sadly it doesn't reduce the noise of these machines though...

John