active-low circuit problem

Thread Starter

Prestyman

Joined Nov 14, 2008
29
I'm returned to a project that I thought I had solved, but has turned into a bit of a headache. Hopefully someone can help.

I have a module with 8 pins that are active-low. I also have a push-button triggering unit with eight pins that each go high when the corresponding button is pushed.

What is the easiest (in terms of soldering parts) way to get the two modules to "talk" to each other.

FYI, my original attempt was 8 transistors, and the necessary resistsors, but that's 40 solder points, which is lot of work if I decided to start making a number of these gizmo's for fellow entertainers.

Is there a better way?

Thanks,
Clinton
<SNIP>
 
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SgtWookie

Joined Jul 17, 2007
22,230
You can use hex inverters; just don't use two of the inverters on each IC.

74xx series are TTL logic. They need to have 4.5v to 5.5v as a supply voltage; they won't work properly if your power supply is above or below that.

You might use 4000 series CMOS logic IC's. They will operate using voltages from 3v to 16v. Their disadvantages are high static sensitivity and low output current.
4069's are hex inverters. 40106's are hex inverting Schmitt triggers.
4093's are quad Schmitt trigger 2-input NAND gates. You can use NAND gates as inverters if you wire the two inputs to a gate together.
Note that ALL unused inputs for 4000 series CMOS gates MUST be tied to either ground or Vdd (V+)
 

Thread Starter

Prestyman

Joined Nov 14, 2008
29
Thanks for the detailed explanaton. It loks like by the time I wire the inputs of the NAND gates together, tie the unused pins to ground, and supply power to the ICs, I'm back to as many solder points as using the transistors. Not quite, but close.

Maybe the answer is to pay to have it done for me. Are there services where someone can supply a printed board with the necessary surface-mounted components already soldered? Whom would you suggest?

Thanks,
Clinton
 

Thread Starter

Prestyman

Joined Nov 14, 2008
29
Still looking for a supplier of printed boards with surface-mounted components. Any suggestions?

~ Clinton
 
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