Data Slicer Question

[ab3ai]

I want to build a slicer using a Max232 but can't find a TL081. Can I use a TL082 instaed? If so, what changes would need to be made?
Thanks!!

 

[gr8amp]

The TL081 is available through Digikey.com. You can also use a LF411 if you want to keep the same pin configuration.

You can use the TL082 if you want. The only difference is that the TL082 contains 2 amplifiers, where the TL081 only has one. Just get the datasheet for the TL082 to make sure you are making the correct connections. The relevant electrical characteristics are the same.

 

[morfis]

If you are using a MAX232 why do you need a TL081 as well?

 

[gr8amp]

If you are using a MAX232 why do you need a TL081 as well?

The MAX232 only provides proper level conversion for the serial port. It does not provide for data slicing functions.

-Jim

 

[morfis]

I realise that but is it not a bit unusual to combine the two interfaces?
Generally the signal from the schmit trigger type circuit doesn't need to be converted from TTL to RS232 levels?

 

[gr8amp]

I realise that but is it not a bit unusual to combine the two interfaces?
Generally the signal from the schmit trigger type circuit doesn't need to be converted from TTL to RS232 levels?

It is not unusual to combine the two interfaces at all, as they serve entirely different purposes. If you take a look at most of the data slicer circuits floating around the net you will notice that the ones not requiring a level conversion are powered off of the port itself. The output levels of these circuits are already rs232 compatable and aren't considered TTL level.

If, for some reason, the slicer is supplied by an external source (say 5 volts as an example) an appropriate level converter should be used to ensure compatibility with all ports. Will some ports accept a TTL level signal properly? Yes, many do (assuming the inversion is accounted for)! Do all of them? No not at all. Designs that "will work" are generally preferred over designs that "should work."

Not knowing the details of the circuit I assume that the circuit is being supplied by a single +5v supply. In which case, I see nothing wrong or strange here.

 

[morfis]

Don't get me wrong, I don't see anything wrong...just thought it odd. I've never actually seen anyone using a combined interface (not that I've actually >seen< many people actually running trunker type software over here!).

 

[gr8amp]

Don't get me wrong, I don't see anything wrong...just thought it odd. I've never actually seen anyone using a combined interface (not that I've actually >seen< many people actually running trunker type software over here!).

Understood. There are many ways of approaching this circuit. Some are more reliable and universal than others. I think most people use the simplest approach, which is what you are describing, and most have good results. Thats what makes this fun

-Jim

 

[rayradio7972]

What make and model is your scanner?
I own a Icom R-7000 and constructing a slicer-interface for it.What op amp will work ?

 

[rayradio7972]

Icom R7000 slicer -interface

What make and model is your scanner?
I own a Icom R-7000 and constructing a slicer-interface for it.What op amp will work ?