ADICON Support Forum Applied Digital, Inc.
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#23409 - 12/23/12 03:02 PM SECU16 and IR detector
carlosk Offline
newbie


Registered: 12/23/12
Posts: 4
I am using a secu16 to determine when the mail comes. The mailbox has an IR TX RX pair, but I cannot get the secu to recognize the change in voltage. I had this working before so I cannot figure out why it's not working now.

I am using a potentiometer to bring down 18V to 5V, the 5V are applied to the IR transmitter with resistance as a current limiter. The same 5V are used fro the receiver. When there is no mail the voltage is 0 (zero) when there is mail the voltage is about 2V so the detector is working. When I attach the leads to the secu16, I read 4V on the secu16 terminal no matter what. If I just go directly from the potentiometer to the secu16, I can see it change state at about 1.5V, but it will never change state when attaching the leads from the IR receiver.

What am I missing?

Thanks

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#23410 - 12/23/12 04:45 PM Re: SECU16 and IR detector [Re: carlosk]
Guy Lavoie Administrator Offline
Beyond All Hope
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Registered: 12/21/02
Posts: 6548
Loc: Montreal, QC, Canada
Sounds like the SECU16 input doesn't want to get pulled down. Testing with the SECU16 input alone (not connected to your circuit) what happens if you put a 1k resistor across the input (input and common): what voltage do you get across the input? If it goes down to about 2 volts then the input is working normally and something would likely be wrong with the IR receiver itself.
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"If you don't know what you're doing, do it neatly..."

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#23411 - 12/24/12 09:56 AM Re: SECU16 and IR detector [Re: Guy Lavoie]
carlosk Offline
newbie


Registered: 12/23/12
Posts: 4
Here are the results

Direct measurement between terminals 4.07 V
With 1K ohm resistance 3.7 V
With 100 ohm resistance 2.0 V

Does this mean anything?

Thanks

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#23412 - 12/24/12 12:38 PM Re: SECU16 and IR detector [Re: carlosk]
Guy Lavoie Administrator Offline
Beyond All Hope
*****

Registered: 12/21/02
Posts: 6548
Loc: Montreal, QC, Canada
It really looks like the input mux chip is blown, at least on that input. Have you tried the same test with other inputs?

The chip is part # 14051. This is a 8 channel multiplexer. They only cost a few bucks each and is easy to replace (in a socket). if you have a source for ICs in your area, try to find a replacement, and maybe a spare too.
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#23413 - 12/24/12 04:59 PM Re: SECU16 and IR detector [Re: Guy Lavoie]
carlosk Offline
newbie


Registered: 12/23/12
Posts: 4
Nothing works, I'm going to get a new chip and see how it goes.
Thanks

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#23423 - 12/29/12 05:33 PM Re: SECU16 and IR detector [Re: carlosk]
carlosk Offline
newbie


Registered: 12/23/12
Posts: 4
I received the replacement chips today, installed one and everything seems to be working. Thank you very much
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#23424 - 12/29/12 06:47 PM Re: SECU16 and IR detector [Re: carlosk]
Guy Lavoie Administrator Offline
Beyond All Hope
*****

Registered: 12/21/02
Posts: 6548
Loc: Montreal, QC, Canada
Good!
_________________________
"If you don't know what you're doing, do it neatly..."

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