R/C railroad locomotive?

Dear Sparky and other,

The EMS Jomar solid state switches have come up several times during the life of this thread. There were no such things available when I flew RC aircraft, or at least I was unfamiliar with them if they were. In other words I don't know what I don't know.

The audio system for the locomotve consists of two components. One is the sound card and the other is a standalone amplifier.

The volume on the sound card is controlled by a momentary toggle. When the toggle is held in one direction the volume goes up until the correct volume has been achieved. When the toggle direction is reversed the volume goes down. The volume on the amplifier use a standard audio control switch like you find on your car radio.

EMS Jomar offers a Opto-isolated E-switch. The EMS Jomar website includes the following description:

"Solid-state replacement for a servo and switch! Adjustable ON point, reversing switch, and LED indicator. Optically isolated for no radio noise problems. Use as ?old timer? ignition cut-off, GLO driver switch, Smoke pump control, On-board starter, etc., 1.5 x 1.5 x .75 - weight .5 ounce! Includes servo connector. Switch up to 24 volts, 20 amps!"

Do you think that this e-switch could control either of the above mentioned volume switches?

Regards,

Britt Harrington Miami, Florida

Reply to
FBritt
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Solid state pot? How about a speed control for a rc car or plane? They vary the output voltage which is the end result of using a pot.

remove my-wife to reply :-)

Reply to
Icrashrc

| Solid state pot? How about a speed control for a rc car or plane? | They vary the output voltage which is the end result of using a pot.

As I mentioned in another post, yes and no.

Mechanical speed controls usually have a few (three or four) large current resistors and a servo to control a switch that picks which one you're using. So they don't give you a smooth range of speeds -- you get to pick one of a few options. They're basically pots, but they usually make some compromises in order to handle much larger current loads.

These are somewhat common on low end electric cars, but I've never seen one used in an airplane (but there's no reason one couldn't be.) But they're really inefficient and unreliable, so people prefer ESCs ...

Electronic speed controls don't adjust the voltage or resistance at all (not by a signifigant degree anyways) -- instead, they turn the current on and off a few thousand times per second. The higher the setting, the more time spent `on' and the less time spent `off'.

A mechanical speed control could replace your pot given the right resistor values (some let you change them, some don't). You wouldn't have a full spectrum of possible values, but you'd have some control. It might be good enough.

An electronic speed control will *not* work. What it will do is introduce a very loud hum (probably louder than anything else) that varies depending on your setting -- the hum will only go away at zero throttle or full throttle.

I believe the original poster said that one volume was just a toggle switch -- up to increase volume, down to decrease? If so, two electronic switches would probably work, one for each direction. Still, I'd personally probably set up something with a standard servo moving the switch -- it would be cheaper, and this isn't a `mission critical' part so if it does fail people won't get hurt :)

Reply to
Doug McLaren

Actually, most speed controllers don't vary the voltage, but use a variable duty cycle. In other words, they turn on and off the full voltage very quickly and vary the amount of "on" time. With a suitable capacitor across the leads, a variable voltage can be seen by the load.

Reply to
Paul McIntosh

The EMS Jomar functions like a solid-state relay. It is either 'open' or 'closed.' The reversing function refers to the fact that your can program the direction the transmitter stick is moved for 'on.' The LED indicates the point at which the MOSFET switchs on. You can set this with the ATV or 'end point' adjustment on the transmitter.

In other words: It won't do what you want.

Reply to
Doug Dorton

There is rec.models.railroad.

DCC (which is remote control via signals in the rails) is discussed frequently.

Good luck

Greg

Reply to
Greg Forestieri

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