While archiving info on old ICs I came into ITT342, a high level logic monostable multivibrator. My question revolves around the connection to the timing components. On which side, "C" or "D" does the resistor connect to? My guess was "D". I couldn't find a data sheet for this old chip. Does the attached make sense?

Edited to correct the drawing.

 

Note the circuit fragment of a 20K resistor connected to Vcc and Pin E, so guess what? An external resistor goes between Vcc and pin E like the applications drawings show.

 

While archiving info on old ICs I came into ITT342, a high level logic monostable multivibrator. My question revolves around the connection to the timing components. On which side, "C" or "D" does the resistor connect to? My guess was "D". I couldn't find a data sheet for this old chip. Does the attached make sense?

It looks like the "m" on your typewriter is stuck.

That chip may be similar to a 7400 chip with slightly different pinout.

http://www.ti.com/lit/ds/symlink/sn74ls123.pdf

 

Note the circuit fragment of a 20K resistor connected to Vcc and Pin E, so guess what? An external resistor goes between Vcc and pin E like the applications drawings show.

As shown in the examples the "E" is an optional internal resistor to use instead of an external resistor.
74121 does a similar thing.

 

It looks like the "m" on your typewriter is stuck.

That chip may be similar to a 7400 chip with slightly different pinout.

http://www.ti.com/lit/ds/symlink/sn74ls123.pdf

Yes, similar to 74121 and 74123. But on these the resistor connection is tied to VCC externlly to use it. Just the opposite of the 342.

Re: M stuck
No, it is old fingers and bad eyesight.

You don't have an internal breakdown of the 74121, 122 or 123 do you that shows specifics of this part of the circuit do you?

 

Yes, similar to 74121 and 74123. But on these the resistor connection is tied to VCC externlly to use it. Just the opposite of the 342.

Re: M stuck
No, it is old fingers and bad eyesight.

You don't have an internal breakdown of the 74121, 122 or 123 do you that shows specifics of this part of the circuit do you?

If it ain't on the datasheets, I ain't got it.

 

Re: 74121 vs ITT342 and the use of the optional internal resistor
See the attached and compare with the ITT342.

 

If it ain't on the datasheets, I ain't got it.

No, it sure ain't. Thus I bring the question to those smarter than I am.

 

No, it sure ain't. Thus I bring the question to those smarter than I am.

Check cd4528. It has a schematic.

http://www.jameco.com/Jameco/Products/ProdDS/13611.pdf

 

Check cd4528. It has a schematic.

http://www.jameco.com/Jameco/Products/ProdDS/13611.pdf

Thanks, but not much help. On the 4538 one side of the capacitor goes to ground. On the 342 the capacitor goes between pins and I'm not sure which side of the capacitor should have the resistor going to VCC.

 

I found this tidbit of information:
It is dual timer made using DTL and can run on 12 volts.

Ahha! Found it! Here using this search: https://www.google.com/search?q=ITT+dtl+logic&ie=utf-8&oe=utf-8

https://www.google.com/url?sa=t&rct...sg=AFQjCNHi8l6D8w14BMyrJ1NJomJE08Er8g&cad=rja

I can't upload the file-- it is too big. The data is on page 34 of section 5.

 

I found this tidbit of information:
It is dual timer made using DTL and can run on 12 volts.

Ahha! Found it! Here using this search: https://www.google.com/search?q=ITT+dtl+logic&ie=utf-8&oe=utf-8

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0ahUKEwiEhMHImcrRAhUIwFQKHaK-BPQQFgg3MAU&url=http://bitsavers.informatik.uni-stuttgart.de/pdf/itt/_dataBooks/1974_ITT_Semiconductor_Product_Catalog.pdf&usg=AFQjCNHi8l6D8w14BMyrJ1NJomJE08Er8g&cad=rja

I can't upload the file-- it is too big. The data is on page 34 of section 5.

Super reference. Lots of hard to find stuff in there, but still doesn't answer my question about which end of the cap to pit the resistor on.
Interesting ... 74124 is a pulse generator not the VCO. !'m gonna spend a few hours looking at this file. Thanks.

 

Look at your first drawing. Locate Vcc, R14 and a 20K resistor in the lower right corner. That's the internal resistor. he top left diagram uses that resistor. The right one, uses an external resistor.

Are you wanting the capacitor polarity? The symbol has an inherent polarity, but generally you would not use a polarity sensitive cap for timing.

 

Look at your first drawing. Locate Vcc, R14 and a 20K resistor in the lower right corner. That's the internal resistor. he top left diagram uses that resistor. The right one, uses an external resistor.

Are you wanting the capacitor polarity? The symbol has an inherent polarity, but generally you would not use a polarity sensitive cap for timing.

The drawing represents my best guess at where the resistor should connect to the capacitor. I'm just not sure that is right. But now that you mention it the polarity of the capacitor is uncertain to me also. I guess the two questions go together.

(edited to add ...)
It looks like the positive of the capacitor would go toward "C" but it doesn't make sense that the resistor would go there.
I'm so confused.

 

Considering the circuit above the + of the cap goes to "C" and the resistor goes to "D" and +V.

 

The drawing represents my best guess at where the resistor should connect to the capacitor. I'm just not sure that is right. But now that you mention it the polarity of the capacitor is uncertain to me also. I guess the two questions go together..

The cap goes between the "c" and "d" with the positive on "c". the resistor connects from "d" to Vcc. or use the internal 20K resistor by connecting "d" to "e".

If this doesn't work let us know and I will try again.

 

The cap goes between the "c" and "d" with the positive on "c". the resistor connects from "d" to Vcc. or use the internal 20K resistor by connecting "d" to "e".

If this doesn't work let us know and I will try again.

That was my conclusion also. I don't have one to play with. Just archiving info on old ICs.

 

That was my conclusion also. I don't have one to play with. Just archiving info on old ICs.

I am glad you asked about the ITT chip. I now have the PDF of that "classic" data book added to my collection. Last I checked, my data sheet directory was over 18GB in size.

 

I am glad you asked about the ITT chip. I now have the PDF of that "classic" data book added to my collection. Last I checked, my data sheet directory was over 18GB in size.

I haven't looked at size but mine must be similar in size. I used to work in places where the techs did not have access to the internet. All technical references had to be available in-house. My data bases are huge.