Trip Amplifier Circuit

[andybarrett1]

Hi All

Thank you for reading .... I have a need for a simple Trip Amplifier circuit .... They used to be all over the industrial world ... But not so much now !

Basically something that looks at a 4-20ma signal and trips a low or high relay depending on my set points. I am at this moment thinking of using a 339 comparator and a couple off bc108 driven relays.

But. I was wondering if anybody had any better ideas or maybe a PIC controller might  do job better ?

I am open to any thoughts .... thank you for reading

Andy

[Marco]

Still quite a few new trip amplifiers for sale, mostly in Britain for some reason.

Could use a TL431 with that BC108 as well.

[Seekonk]

A  TL431 is a great choice if you like component level building.  These easily drive small relays by themselves if a dry contact is needed. I am getting spoiled by those Arduino clone mini328 boards that can be bought for $2-3 for these small jobs.  If a switch transition at a set voltage was all you wanted, life would be simple.  When you add in time delays and hysteresis a small micro wins hands down.   In my opinion spending 75 cents more for the gold boards is worth it.

[andybarrett1]

Hi

Looking at the TL431.... But it looks a little sensitive 

BR
Andy