OK :)
I'll try that.

On Wednesday, April 16, 2008 9:14 AM [GMT-3=CET],
Spehro Pefhany  wrote:

> At 07:53 AM 4/16/2008, you wrote:
>> Hi fellows,
>> 
>> I'm trying to desing a very simple SR circuit to control
>> two 24VDC signals coming from two CAMs inductive
>> sensors) and one 24VDC output which is connected to a
>> PLC input. (noisy machine) 
>> 
>> In most of the desings I've ended up with this (block)
>> configuration opto--\
>>        logic--opto
>> opto--/  |
>>          |
>>        source (taken from PLC)
>> 
>> For the logic part I used a 555 with reset and trigger
>> tied to positive through 100K resistor.
>> Since the 555 used 18V max,... I have calculated a 18v1w
>> zener with a 100ohm1/2W resistor limitation to power the
>> kit. 
>> 
>> I've also thought about a 12F, but I don't want a DC-DC
>> converter,... unless it would be the best and safer way
>> to do this task. 
>> 
>> True table
>> S     R    Out
>> REdge x     1
>> x     Redge 0
>> 
>> Is there any chip out there that works over 24VDC
>> directly? 
>> Should I have to desing this with Op amp?
>> The challenge is to desing the SR on the 24VDC rail,
>> with the less number of componentes as possible.
>> 
>> I'll appreciate any hint .
>> 
>> Cheers regards.
>> Dennis (lurker)
> 
> How about a couple of cross-coupled BJTs with load and
> base resistors? (an RTL, and I don't mean
> register-transfer-logic, S-R FF). 
> 
>> Best regards,
> 
> Spehro Pefhany --"it's the network..."            "The
> Journey is the reward" speff@interlog.com            
> Info for manufacturers: http://www.trexon.com Embedded
> software/hardware/analog  Info for designers: 
> http://www.speff.com  


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