Looking for a Rheostat, and not break the bank

[Justplanecrazy]

I'm trying to find a source for a Rheostat with the given performance:

Voltage from source: 12V
Amperage from source: 3A
Resistance range: 10-350 Ohm (approximate)
Turning radius: 300 degrees +/- 30 degrees

so far the one that has been useful is the RES50R from digikey and it's beefier than i really need. The cheap stuff from Radioshack doesn't have the performance values i'm looking for so i'm looking for a midpoint between the two.

Who has a good selection of rheostats in this type of application?

Thanks all...

 

[Roff]

What are you actually doing with the rheostat? There are many ways to skin a cat.

 

[Justplanecrazy]

Its used to control lighting intensity of neon bulbs.

The one i'm using works fine, it's just oversized for the application. I'd like to find a slightly smaller unit that is also of a lower cost. The RES50R is currently $20.91, anything cheaper?

 

[jrz126]

Is it 12V AC or DC? (I'm pretty sure it is AC, but I figure I may as well ask) and are these just little bulbs or long tubes?

 

[Justplanecrazy]

12V DC current.

The bulbs are a 9" neon tube, commonly used in custom car shops.

 

[Nigel Goodwin]

12V DC current.

The bulbs are a 9" neon tube, commonly used in custom car shops.

If it's a neon lamp it requires high voltage, so it would need an inverter inside (which of course it may have) - but I don't know how it would respond to lowering it's supply voltage anyway?.

As your larger rheostat presumably works well enough to satisfy you?, you could use a simple transistor to amplify a small potentiometer.

Your original specifications quoted 3A, is this the current the light takes?, and have you measured it?. It seems excessively high for a simple low power light.

Something like this should work, depending on your current requirements.

 

[Justplanecrazy]

here is what i'm looking at:

i'm using these as an aftermarket lighting product in the aviation industry.

the voltage from the aircraft is either 12V or 24 V.

power is first supplied from the battery to the switch so that the sytem can be isolated there before hitting the other components incase of a short or other problem.

if the supplied voltage is 24V its going to a converter to 12V, then to the rheostat. the power then goes to the neon bulb power inverter, which we've measured recieves about 1-2.2amps at its connecting terminals.

the whole system works great, i'm just looking to find a cheaper rheostat to lower component costs.

 

[Nigel Goodwin]

i'm using these as an aftermarket lighting product in the aviation industry.

the voltage from the aircraft is either 12V or 24 V.

power is first supplied from the battery to the switch so that the sytem can be isolated there before hitting the other components incase of a short or other problem.

if the supplied voltage is 24V its going to a converter to 12V, then to the rheostat. the power then goes to the neon bulb power inverter, which we've measured recieves about 1-2.2amps at its connecting terminals.

the whole system works great, i'm just looking to find a cheaper rheostat to lower component costs.

From that, I presume it's for a commercial product then?, you intend selling these to other pilots?.

If that is the case I would suggest doing it in a much more professional manner - using PWM to control it, which will give vastly greater efficiency, but no where to warm your feet :lol:

 

[nbucska]

Neon tube or fluorescent tube: cold cathode or heated oxide cathode?
NT: You can control intensity with pulse width modulation.
FT: If you reduce intensity, you must maintain the filament temperature
otherwise the lifetime will be shortened.

You can look up patents,how this is done (<www.uspto.gov> )

 

[Justplanecrazy]

it's a project that i inherited to make better and more effecient, so thank you for the ideas so far.

the bulbs used currently are 9" neon, but i'm in the process of testing cold cathode tubes.

i'm researching the use of a pulse width modulator for this particular application, thanks guys.