Rob Flinn
Well-known member
I'm planning on building a C12(ish) mic & have been looking for places to get the 30M, 250M resistors from wthout having to buy 5000 or spend £20 on each. Anyone point me to some suppliers ?
Where to buy high ohmic resistors in small quantities at sensible prices ?
- Thread starter Rob Flinn
- Start date
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JR
JR
david-p
Well-known member
I get all mine from mouser.com, but I now see that you are in the UK -- Sorry for not noticing! Have you tried Maplin or RS Components?
David
David
0dbfs
Well-known member
You can also get some TRW carbon glaze resistors from ebay if you want some older NOS parts. I picked up a couple packs of 100M and they are large but nice. I'll stock up on others too if the needs arises.
Like these:
Cheers,
jb
Like these:
Cheers,
jb
Rob Flinn
Well-known member
Thanks for the tips.
Funny I never thought of ebay for these more obscure value resistors, but it seems if you can wait for delivery from hong kong they are available, albeit rather large in physical size.
Maplins have a max of 10M, & RS have very expensive resistors in some of these values that look like film caps.
Funny I never thought of ebay for these more obscure value resistors, but it seems if you can wait for delivery from hong kong they are available, albeit rather large in physical size.
Maplins have a max of 10M, & RS have very expensive resistors in some of these values that look like film caps.
MagnetoSound
Well-known member
Rob,
RS have 100M and 1G values pretty cheap:
http://uk.rs-online.com/web/c/passives/resistors/through-hole-fixed/?sort-by=P_breakPrice1&sort-order=asc&sort-option=Price&applied-dimensions=4294789091,%204294875298,4294882864&lastAttributeSelectedBlock=4294956957
RS have 100M and 1G values pretty cheap:
http://uk.rs-online.com/web/c/passives/resistors/through-hole-fixed/?sort-by=P_breakPrice1&sort-order=asc&sort-option=Price&applied-dimensions=4294789091,%204294875298,4294882864&lastAttributeSelectedBlock=4294956957
Rob Flinn
Well-known member
Thanks Dan, but they aren't values I need, I always check RS first, because I have a trade centre about 3 miles away.
s2udio
Well-known member
I can see your problem Rob....
Farnell and RS offer the best deals in the smd line...
I had to make up some odd value hi onmic resistors.... use the low price 5% types to make up the value you want
...mount on a little piece of veroboard,(can be made QUITE small ) ,add a couple of legs then coat in epoxy or pcb lacquer and bobs your uncle.
No discernable difference !
Or pay a high price for the 1% types...ouch
http://uk.farnell.com/te-connectivity-cgs/rh73h2a30mktn/resistor-0805-30m/dp/1174520RL
Farnell and RS offer the best deals in the smd line...
I had to make up some odd value hi onmic resistors.... use the low price 5% types to make up the value you want
...mount on a little piece of veroboard,(can be made QUITE small ) ,add a couple of legs then coat in epoxy or pcb lacquer and bobs your uncle.
No discernable difference !
Or pay a high price for the 1% types...ouch
http://uk.farnell.com/te-connectivity-cgs/rh73h2a30mktn/resistor-0805-30m/dp/1174520RL
Rob Flinn
Well-known member
s2udio said:I can see your problem Rob....
Farnell and RS offer the best deals in the smd line...
I had to make up some odd value hi onmic resistors.... use the low price 5% types to make up the value you want
...mount on a little piece of veroboard,(can be made QUITE small ) ,add a couple of legs then coat in epoxy or pcb lacquer and bobs your uncle.
No discernable difference !
Or pay a high price for the 1% types...ouch
http://uk.farnell.com/te-connectivity-cgs/rh73h2a30mktn/resistor-0805-30m/dp/1174520RL
An interesting concept, but I'm guessing you would need to be a little careful about what board & epoxy you're using, since at hi Z they could affect the spec ?
CIBA have always used their best stuff for Araldite (what you buy from a European hardware store). The Yanks didn't always do this.Rob Flinn said:
Calrec used Araldite (normal) to encapsulate the High Z end of their mikes in da old days.
Rob Flinn
Well-known member
Ok that sounds reasonable, but if you solder it to veroboard & encapsulate it then that becomes part of the equation too I'm guessing.
But it sounds very worth a try, I guess it's possible to do with no encapsulation at all.
But it sounds very worth a try, I guess it's possible to do with no encapsulation at all.
s2udio
Well-known member
Hi
Sorry missed the posts.
Araldite is what i used for mine ...the 30 min quick set is fine .And used for years as stated.
A small coating then quickly into a bit of preprepared tube heatshrink to fit...heat,... leave to dry thouroughly.
A couple of years ago now ,,,,,but i think they were in the range of 1-2 gig , no probs from what i can remember.
Or leave in free air (moisture) or just heatshrink..............Oh shit just thinking maybe i should go into production.
CustomHighOhms... ;D
Sorry missed the posts.
Araldite is what i used for mine ...the 30 min quick set is fine .And used for years as stated.
A small coating then quickly into a bit of preprepared tube heatshrink to fit...heat,... leave to dry thouroughly.
A couple of years ago now ,,,,,but i think they were in the range of 1-2 gig , no probs from what i can remember.
Or leave in free air (moisture) or just heatshrink..............Oh shit just thinking maybe i should go into production.
CustomHighOhms... ;D
0dbfs
Well-known member
Is Araldite a high impedance adhesive? Is there measurement data?
Thx,
jb
Thx,
jb
s2udio
Well-known member
The dielectric properties are in the specs........about 20kv per mm
You need to be careful with ancient high value resistors.0dbfs said:
At Calrec, we had serious problems finding a reliable source in da old days. Many old high value "resistors" didn't obey Ohm's Law but were more like crappy diodes.
Modern high value resistors are MUCH better.
Andy Peters
Well-known member
ricardo said:
I've used Ohmmite Slim-MOX or Mini-Mox in this goofy application where I need to measure the dosage from the beam of a transmission electron microscope. It's simply a couple of 5 G resistors and a fA-input op-amp on some Rogers duroid. The input to the op-amp is simply an aluminum plate of known size, and the beam induces a tiny current in that plate. The board has to be scrubbed absolutely clean, and I can't really bench test the thing.
-a
ricardo said:
Many cheap condensers (e.g.eltrects) use a reversed diode as high-ohmic grid/gate resistor, depending on leakage current..
Jakob E.
Yes. And this limits the max. spl and distortion performance in many common circuits. :'(gyraf said:
There are circuits where this is less of a problem. Scott Wurcer has some in his Linear Audio series of articles. Next episode will be out next month.
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