MS-20 w/timer

homer

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I've got a couple of JoeD timer chip that I'm going to use to build a couple of timers, one for a ms-20 and one for a 49-425. My question is do I have to use a 5 v relay on the ms-20 or can I use a 10K resistor in its place like Tinhorn posted at one time awhile back? And also if I use the 5 v power from PIR do I still use a 1 K resistor on the LED or will the value change?   Thanks Homer
 



davered1

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Homer,

If you mod the ms 20 with the 10k resistor you don't need the relay on ms20 board.The relay just completed a circuit to trigger the timer.just be sure you hook it up like tinhorns post below.

You will still need the 1k resistor For the LED in the schem for timer.

Brians chip and board can be hooked up the same, hope this helps?

Dave

http://www.nightowl.net/~tinhorn/MS20BoardMod5v2.jpg
 

homer

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Thanks Dave , Thats what I thought but did'nt know for sure. Now I just have to find the time to do it.
 

ArkansasElkHunter

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One thing to check is does JoeD's timer take a positive pulse or a negitive pulse.  The MS20 has a negitive pulse, ie its 5v until triggered then goes to 0.  The RS is just the opposite.   Brians chip takes a negitive pulse but If I remember a post way back when, I think brian gets lower power consumption because of this and he mentioned that his pinout was different. If that true a simple inverter will work for you.    I havent had any experiance with the JoeD timer but maybe someone else can add to this.  
Either way, one of the PIR's will work as is and the other will need an inverter.
 


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