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Goldmine Vactrols 10 for $2.99, only a few hours left
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Goldmine Vactrols 10 for $2.99, only a few hours left
Joe_D
Just saw this. Goldmine Vactrols haven't been as cheap lately as they were before. They are on sale today only 10 for $2.99. Limit one package.

Sorry for the late notice -- just saw it myself.

https://www.goldmine-elec-products.com/prodinfo.asp?number=G15396C
cackland
Nice, was just looking at getting some vactrols.

Thanks for sharing.
EATyourGUITAR
these are B stock silonex NSL-32. most of them work. they are all different resistance ranges and curves. there will be sorting or hand matching if you want a specific curve and range. just a heads up. I had good results with them but I would never use them in something for mass production. one side has really short leads that are not breadboard compatible. the leads are like a flat metal ribbon. order some alligator clips. don't blow the LED when you get it on the breadboard. try not to exceed 5mA. 10mA is really close to failure.
Joe_D
Thanks for the heads up. I'm just getting them to experiment with, mostly in simple passive circuits. As I'll need to limit current, which will be coming in at typical modular levels, do you have a trusted resistor value that you have found works well in series before these vactrols?
maltemark
I am looking for silonex vactrols for an optodist build - if anyone would help a guy out for the cost of p+p and the vactrol, I'd be very happy. Tried to find some in EU but no luck yet
EATyourGUITAR
Joe_D wrote:
Thanks for the heads up. I'm just getting them to experiment with, mostly in simple passive circuits. As I'll need to limit current, which will be coming in at typical modular levels, do you have a trusted resistor value that you have found works well in series before these vactrols?


if you want to setup in your head a worst case scenario of +10v and 5mA then you apply Ohms law to arrive at 10/0.005 = 2000 Ohms = 2K

if you also want to figure out what happens when +12v comes through a jack tip to the vactrol LED side you can do 12/2000 = 0.006 = 6mA

it is extremely unlikely to have +/-12v in modular signals so even if it happens briefly it should not result in vactrol failure.

this also assumes that the LED will not be destroyed by -12v. probably safe but you should always ask the question and check the datasheet. reverse 50v for example will destroy most LED's. it is a two step process. first you get enough voltage to get into the zener region (reverse breakdown) of the diode. then the diode resistance drops a significant amount. then the heat generated from that massive current cooks and vaporized the junction until rapid failure. it happens in milliseconds.
Joe_D
EATyourGUITAR wrote:
if you want to setup in your head a worst case scenario...

Thanks for taking the time to write that up!

EATyourGUITAR wrote:
first you get enough voltage to get into the zener region (reverse breakdown) of the diode. then the diode resistance drops a significant amount. then the heat generated from that massive current cooks and vaporized the junction until rapid failure. it happens in milliseconds.

Yeah, I’ve made a few LED’s go “Pfft!” in (non-Eurorack) music projects due to inattention to current/voltage levels or shorting while prototyping. It happens pretty quickly!

Appreciate your help.
3vcos
their spec says the vactrols are less than 400ohms when on. for lowpass gates we usually want 10s of ohms or so. I wouldn't try these in LPG applications unless your expectations are pretty low.
Joe_D
3vcos wrote:
their spec says the vactrols are less than 400ohms when on. for lowpass gates we usually want 10s of ohms or so. I wouldn't try these in LPG applications unless your expectations are pretty low.


Thanks. For $2.99, my expectations are pretty low. Mr. Green I did see that some NLC modules use this model vactrol, and I am a big NLC fan, so if I can get a few decent ones (that I don't accidentally blow up eek! ), I'm thinking that they'll find a home eventually.
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