LM311P circuit - connections, wiring and diagram

Hi Clemens,

thank you for your fast reply.

First of all I want to have a very fast switching circuit, so 1k should 
be fine then?

The hysteresis should be like 0.05V for signal Voltages e.g. between 2.3 
and 2.7 Volts ( so V1 = 2.475 and V2 = 2.525 Volts).

I know that I drew the pin arrangement, but that is even my question 
whether I planned the right wiring (IC, BNCs, resistors, power supply 
...) ...

Is the IC with an open collector the right thing for me?
The advantage is, that the current to V_out is not going through the IC 
itself and it therefore should be rather restistant towards "over 
current damage".

Thanks
Valentin

Hi Clemens,

you are right. "very fast" is not precise.
It would be great to have a circuit with a maximal reaction time of 
about 50µs.

The output signal is used a trigger signal to enable phase aligned 
optical measurements. Usually a rising edge of 2.4V should already 
trigger the device (accordingly to TTL logic on the web).

You are certainyl right, when the circuit switches to 0V the current 
gets grounded through the IC.

So since there are no major concerns or people saying "that ain't gonna 
work", I guess it is worth trying it.

Thanks!
Valentin

That looks a bit dangerous, because the user can adjust the upper 10k 
and the lower 470k Pot to produce a short circuit of the power supply.

Its better to replace them with a single pot and a series resistor which 
also eliminates one adjustment point.
As mentioned you probably should increase the value of the hysteresis 
pot by a large degree.

Hi Matzetronics,

Good point with the short circuit possibility. Since I need the 
adjustment I will just add a 10k resistor or so to the lower pot.

As far as I calculated it, the dimensions of the pots are just so, that 
I can adjust everything I need.
So if I increase the hysteresis pot, the hysteresis window decreases. 
Since my signal (gained from a hot wire signal) is quite noisy, I need a 
rather big hysteresis.

So what is the benefit of increasing the hysteresis pot?

Thanks
Valentin

Ok, I found the problem.
I had it right in my calculations but had it wrong on my plan.

So, attached the improved circuit plan (changes marked red):
1. preventing a short circuit
2. the hysteresis pot being the 470k to adjust the levels I need

That current design should do it?

Thanks everybody for your great help and the fast responses!

Valentin

Thanks, awesome!