germanium diode oa91 alternative- project

[kevinkevinx2]

im planning to do this project for school sciance fair: http://www.creative-science.org.uk/mobile_LED.html
I found out the germanium diode oa91 was discontinued and unavailable unless ordered online. due to certain due dates, ordering would be my last option. is there any equivalent or alternate diode that i can use?

 

[JimB]

You should be able to find a 1N4148 which will work OK for this circuit.

JimB

 

[ronsimpson]

Looking at the picture there is a small glass diode.
The 1n4148 and 1n914 come in that glass package. If you can't find what you want just try any small glass diode. I started out getting parts out of dead TVs and radios.

 

[MikeMl]

A silicon diode like a 1n914 will have greatly reduced sensitivity as a 1Ghz RF detector compared to a point-contact Germanium diode like the OA91, if it works at all. A small-signal Schottky would be a better choice than a 1n914.

I have dozens of Ge uWave detector diodes around here. Where are you located?

 

[audioguru]

The OA91 was available in Europe. Here in North America we used 1N31A germanium diodes about 60 years ago.

 

[4pyros]

and still available here;
https://www.weisd.com/ProductView.php?PN=1N31A

 

[audioguru]

Look at the high price for that "equivalent" for a cheap old diode.

 

[4pyros]

Ya its a "replacement part"

 

[audioguru]

I don't think that NTE makes anything. They simply buy parts made by other manufacturers, rub off the original part number and put on their own part number then sell it at a much higher price. I forgot to add their "hoarding fee".

 

[4pyros]

If the OP wants to look around some more he may find something more suitable.
The web site said it has to have the wire in it for it to work, there should be more alternatives out there.

 

[kevinkevinx2]

A silicon diode like a 1n914 will have greatly reduced sensitivity as a 1Ghz RF detector compared to a point-contact Germanium diode like the OA91, if it works at all. A small-signal Schottky would be a better choice than a 1n914.

I have dozens of Ge uWave detector diodes around here. Where are you located?

Hawaii

 

[MikeMl]

Hawaii

I can throw a couple into a first class envelope. How quick do you need it? Contact me using the forum's Private mail system....