Converter 0-2mA to 0-10V

[Stefan_i_motala]

Hi

I have an old lighting desk Grossman from Denmark that works with an old controll standard 0-2mA out. I also have the dimmers 48 channels. Have someone build a converter from 0- +10V to 0-2mA and 0-2mA to 0-+10V ? I whant to connect my other 0-10V light controllers to the Grossman dimmers and my Grossman controller to my other analog controlled dimmers. I have a factory built demultiplexer from DMX512 to 0-2mA that works fine but I also whant my other analog euqipment to work with the Grossman.

 

Thanks

Stefan Johansson

Motala Stagelight Sweden

www.scenljus.com

[MarkPAman]

a converter from 0- +10V to 0-2mA and 0-2mA to 0-+10V ?

 

Some confusion here I think. ;)

 

Volts & Current (Amps) are different things. Although one will affect the other, you can not "convert" between them.

 

What voltage does the Grossman put out?

[ajh51]

Hi Stefan,

 

It's pretty easy to convert between the 0-2mA and 0-10V so long as the power supply of the desk will output at least 10v, just put the current into a fixed resistance to do the conversion.

 

Using ohms law (V=IR) then we can see that to get 10V out when you put 2mA in you need a single resistor of 5000 Ohms. That MAY be all you need, it will depend if the analogue equipment you are trying to control draw any current from their inputs. If they do, then some of your 2mA will be going into the input of your equipment, not the resistor which will mess up the conversion. If this happens you can use a MOSFET input opamp to buffer the 0-10V from the top of the resistor into the equipment.

 

This would be an easy build if you are handy with a soldering iron - come back to me if you need more info.

 

Mark - current signals are used a lot in industrial applications. The voltage of the signal is not defined, the current is. The advantages are that:

(1) the impedance of the wire used to transmit the signal can't attenuate it so long as there is enough voltage headroom to drive the current.

(2) The signal is less susceptible to interference from electro-magnetic interference.

 

It actually makes a lot of sense in an analogue lighting control situation where the desk may be long way (hence high impedance cables) from the dimmers.

 

Andy.

[MarkPAman]

Mark - current signals are used a lot in industrial applications.

 

OK fair enough.

 

That's something I've learned today.

 

Thanks ;)

[drsound]

Speak to PR Electronics, they do a range of converters to change between common industrial signal ranges. Get one that will take a nominal 0-20mA signal input and give 0-10V output and then use the internal software to change the scaling to give 100% output at 2mA. If you wanted to be really clever you could even map a look up table to give funky dimmer curves. Hours of fun.