[GreenKeys] Re: Voltage and Current

[WA5CAB at cs.com]

EE Mode On.

12 volt constant current supply is a contradiction in terms, at least in the 
context of this group where most machines run on loops @ either 20 or 60 mA.  
Or to put it another way, a 12 volt supply with electronically controlled 
series resistance (i.e., a current regulator) will not push a square wave current 
wave form through either M15 or M28 holding magnets.  Consequently, the error 
rate will go sky high and the range will go to zilch.

EE Mode off.
Greasy fingered tech mode on.
It won't work. 

In a message dated 1/23/2007 9:47:21 PM Central Standard Time, 
drhouse at nadcomm.com writes: 
> Bob,
> 
> 48 volts should be the minimum used to operate selector magnets.   
> Personally I prefer -130vdc 62.5 ma but you know that I suppose.
> 
> Don
> K9TTY
> 
> 
> On 23 Jan 2007, at 8:42 PM, Bob Camp wrote:
> 
> Hi
> 
> A typical constant current loop control transistor puts a fixed bias  
> on the base (or gate) and resistance from the emitter (or source) to  
> the other side of the bias. As the current in the resistor drops the  
> current in the transistor increases.
> 
> These days you can do some interesting things with a switching  
> regulator. Twelve volt supply constant current loops anybody?
> 
> 

Robert & Susan Downs - Houston
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