Many years ago I bought some bridge rectifiers to work on some electrical project on the RR layout. I am trying to remember their benefits. When used do they allow accessories to run cooler? What else are they used for?
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What I use a bridge rectifier for is to convert a Williams engine to straight forward or reverse only. I got upset with the way one of my engines always started in the wrong direction and so I asked around on the forum how to change it straight forward or reverse only and was told to use a 6 amp 50 volt bridge rectifier.
One note about the bridge rectifier; you will gain a slight power increase(about 5 %) in the engine as you won't be going through the circuit board for direction control.
Lee Fritz
They commute ac to dc and you get both halves of the ac. Giving you a higher average dc voltage than with just one diode. Which requires less capacitance to filter the ripple out.
If you run accessories on dc instead of ac, they don't buzz...but you have to pay attention to the dc voltage you end up with...and if dc is appropriate for the device.
Whether it's better or not depends entirely on the details.
Thanks Jack, my problem is I have a Lionel Gateman that even when I set the voltage 9-10 volts it set burns up the solenoid after a few days of use on a store layout. Was wondering if the bridge would allow it to run cooler
Originally Posted by cbojanower:
...even when I set the voltage 9-10 volts it set burns up the solenoid after a few days of use on a store layout...
Have tried to roll your own? A custom wound coil is probably what you are needing.
That would be the answer to it's overheating. I had a similar issue with a solenoid in a semaphore. I need to find a different way to operate it so that it doesn't stay on so long.
Difficult with a gateman if you park a train over the sensor. Lionel used to sell rheostats for this purpose, inserting it in series with the voltage driving the accessory.
I think now your reference to a diode bridge was in using the diodes in the bridge in series with the driving voltage to reduce the voltage. Not as a rectifying bridge, but for the purpose of just dropping the voltage. Just a single diode would reduce the voltage to about a third of it's former heating power, but the solenoid may not activate. One thing though is that a solenoid needs a large voltage to pull in and can be maintained with a much smaller one. So in that case the single diode rectifier may pull the solenoid in since the voltage still goes to peak but the average value of the voltage is much lower.
Another use of a diode and some resistance is to charge a capacitor to a peak value which will discharge when it is connected to pull in the solenoid, but the resistor will limit the current for the time when the solenoid is held in for long periods. You would have to experiment with a diode in series with a resistance and then a capacitor across the solenoid. I would use maybe a 1000 uF capacitor to start with and perhaps a 10 ohm resistor in series with the diode coming from the voltage source. A wild guess without knowing the requirements of the solenoid. But doing something is still data for knowing what to change to make it work.
