Ceramic Resonators (zx81)

[spodula]

Anyone know where i might get hold of a Ceramic resonator for the zx81? Cant seem to find one anywere at 6.5Mhz

I've tried using a standard Crystal, but this doesnt seem to work.

Anyone got any ideas?

[sirmorris]

They are quite hard to find. Your best bet would be someone's scrap box. I may be able to help but it'll be a few days until I manage to root out some old boards.

Does the crystal need a couple of caps to kick it off? I've always understood that some crystals will need 10-20pf of load in order to start working?

C

[PokeMon]

Have found them in Digikey shop:
http://search.digikey.com/us/en/product ... -ND/350459

Maybe you have to buy all 500 (USD 0,22 per piece), I am not sure.

Or at Reichelt, german distributor for EUR 1,00 per single piece:
http://www.reichelt.de/Filter/SFE-6-5/i ... 307a4f43fe

[Andy Rea]

Hmmm Odd i have used 6.5336Mhz crystals they are much easier to source without problems (on an issue 1 board) i wonder if that extra 1K resistor thats on the issue 3 boards stops it from working ?

Andy

[spodula]

Wierdly, it appears to be oscilating, just at the wrong frequency.

I shall try some of the links posted. Thanks!

[Paul]

Or at Reichelt, german distributor for EUR 1,00 per single piece:
http://www.reichelt.de/Filter/SFE-6-5/i ... 307a4f43fe

Maybe Rich would like to sell those?
@Rich: would you like me to order some and send them to you?

[sirmorris]

Wierdly, it appears to be oscilating, just at the wrong frequency.

Hmm, a very talented hardware hacker once told me about slowing down machines by loading their crystals with capacitors. I think most crystals have the need of a small load, but you can affect them by altering this. Could that be an issue?

C

[RWAP]

Or at Reichelt, german distributor for EUR 1,00 per single piece:
http://www.reichelt.de/Filter/SFE-6-5/i ... 307a4f43fe

Maybe Rich would like to sell those?
@Rich: would you like me to order some and send them to you?

Yes I could sell these I guess - but 1 euro each means I need to sell for about £2 each, so see if you get a good price for 50?

The German ones have 3 legs on the pictures - the American site shows 2 !!

[sirmorris]

They need 3 legs.

C

[Paul]

I just wonder what this might be.
http://www.pollin.de/shop/dt/MjU5OTQ3OT ... ilter.html
It's a lot cheaper...
Anybody any ideas? Or even knowledge?