Hi guys, I'm in the half of engineering, so I don't have much experience yet. So I would appreciate your help to tell me how I can replace those transistors, because I think they are very old.

If it helps to you, I need them for a pacemaker, this one:

http://www.seekic.com/uploadfile/ic-circuit/2009720203250264.gif

If you know an easier way to build a pacemaker (it doesn't have to keep someone alive, of course, it just needs to do a similar function as the real ones do. It is a homework), would be great too.

Thanks!

 

There may exist cross reference lists from JEDEC numbers to NTE. Be aware that NTE components may cost up to 10 times the price of the original component because the are sold as quantity 1 instead of in bulk.

The second approach is to re-engineer the circuit by developing a set of requirements for the transistors and coming up with a modern equivalent. You might also have trouble with the 1N34A germanium diode as well.

 

Shouldn't this be in the "Homework Section"?

 

2N35; germaniaum NPN, 25v 8mA
2N255; germanium PNP,15v 3A 20W
the diode is germanium too...

And the flashing Neon indicator is probably showing the circuit is from the age before LEDs, or before they were standard.

Is there any reason you want to build a 1960's pacemaker circuit?

If you seriously want to build one why not use a 555 timer, and any common power transistor to drive the coil?

 

Thanks! I looked for the list and did find replacements,but you're right, they're way too expensive...

 

There may exist cross reference lists from JEDEC numbers to NTE. Be aware that NTE components may cost up to 10 times the price of the original component because the are sold as quantity 1 instead of in bulk.

The second approach is to re-engineer the circuit by developing a set of requirements for the transistors and coming up with a modern equivalent. You might also have trouble with the 1N34A germanium diode as well.

2N35; germaniaum NPN, 25v 8mA
2N255; germanium PNP,15v 3A 20W
the diode is germanium too...

And the flashing Neon indicator is probably showing the circuit is from the age before LEDs, or before they were standard.

Is there any reason you want to build a 1960's pacemaker circuit?

If you seriously want to build one why not use a 555 timer, and any common power transistor to drive the coil?

hahaha no special reason, appart that I actually don't know how to build the pacemaker by myself. As I said before, I'm just in half of the career, so I'm still quiet ignorant at some things, specially with analog electronics, cause I haven't taken that subject yet, so I just googled it and found that diagram...

 

Shouldn't this be in the "Homework Section"?

Just click the triangle in the upper, right corner and the moderators will decide.

 

...
...cause I haven't taken that subject yet, so I just googled it and found that diagram...

I would "just google it" some more, and find ANOTHER diagram.

One from this century, or at least the later part of last century.

 

I would "just google it" some more, and find ANOTHER diagram.

One from this century, or at least the later part of last century.

Yup, found a very useful PDF and I'm using it to build a newer one. Thanks!

I'm posting the PDF if someone is interested in taking a look:

https://galileo.seas.harvard.edu/images/material/3794/1321/CardiacPacemakerdesign.pdf