Hello,
Has anyone ever come across a series of resistive opto isolators that can handle higher cell voltages than the popular types such as the Xvive VTL5 line and the NSL photo type opto isolators? I see most of these have a max cell voltage of about 60 volts and max power of about 50mW.
Reason I ask is that I'm implimenting some switchable mods on 12ax7 cathodes. All is well with the aforementioned opto's until I get to the cathode follower, at which point we are seeing voltages around 160volts.
It would be nice to have a means of switching in various bypass caps and resistors in parallel with the cathode resistors on the cathode follower sections.
Thank you!
Best,
Phil D
Has anyone ever come across a series of resistive opto isolators that can handle higher cell voltages than the popular types such as the Xvive VTL5 line and the NSL photo type opto isolators? I see most of these have a max cell voltage of about 60 volts and max power of about 50mW.
Reason I ask is that I'm implimenting some switchable mods on 12ax7 cathodes. All is well with the aforementioned opto's until I get to the cathode follower, at which point we are seeing voltages around 160volts.
It would be nice to have a means of switching in various bypass caps and resistors in parallel with the cathode resistors on the cathode follower sections.
Thank you!
Best,
Phil D
Why not use FETs like everyone else. The 2N7000 fits the bill as does the J112 jFET.
Not sure switchng 160volts is a viable proposition.
An opto coupler may work; https://uk.rs-online.com/web/c/displays-optoelectronics/optocouplers-photodetectors/optocouplers/
Not sure switchng 160volts is a viable proposition.
An opto coupler may work; https://uk.rs-online.com/web/c/displays-optoelectronics/optocouplers-photodetectors/optocouplers/
Just a thought, you could drive a high voltage transistor with a standard opto device of your choice from a low voltage supply from within the equipment in question.
How about an optoMOS optocoupler/solid-state relay? For example
https://eu.mouser.com/ProductDetail/IXYS-Integrated-Circuits/LCA110?qs=AN9n7QNm0jJpFrXJ0Ydzyw==
https://eu.mouser.com/ProductDetail/IXYS-Integrated-Circuits/LCA110?qs=AN9n7QNm0jJpFrXJ0Ydzyw==
Thanks all, sounds you have some great ideas. I will take that as "there are no resistive opto-couplers who's cells handle over 160 volts"!
An engineer where I work directed me to the line of NSl opto's for the application I described to him. I ordered a few of them and breadboard and tested them with a sine wave while looking at the inputs and output with a scope, as well as the timing. What I did was implement an RC between the LED and LED current resistor to play with time constants for controlling the time window of the opto going from full resistance to minimum resistance.
I had to assume the potential for audible "Pops" if I were to discreetly just switch in an out various resistors and caps either in series or parallel with cathode resistors so, the little LED timing thing seemed like a reasonable idea as to dissipate any difference in potential over a time - short enough to not hear but fast enough to no make any audible noise. I haven't yet done this in a real life tube/cathode situation but it looks good on scope and paper. Thats is merely the first order of analysis on that. I just figured if this would work, then, I'll just keep things in the family.
But, it looks like I may need to check out some other means of accomplishing this, and I will be looking into your suggestions.
thank you for your generous feedback on this, I'm really looking forward to making some well functioning and quiet cathode switchable mods. Very useful for certain guitar tube amp tone and gain flexibilities.
Best,
Phil D.
An engineer where I work directed me to the line of NSl opto's for the application I described to him. I ordered a few of them and breadboard and tested them with a sine wave while looking at the inputs and output with a scope, as well as the timing. What I did was implement an RC between the LED and LED current resistor to play with time constants for controlling the time window of the opto going from full resistance to minimum resistance.
I had to assume the potential for audible "Pops" if I were to discreetly just switch in an out various resistors and caps either in series or parallel with cathode resistors so, the little LED timing thing seemed like a reasonable idea as to dissipate any difference in potential over a time - short enough to not hear but fast enough to no make any audible noise. I haven't yet done this in a real life tube/cathode situation but it looks good on scope and paper. Thats is merely the first order of analysis on that. I just figured if this would work, then, I'll just keep things in the family.
But, it looks like I may need to check out some other means of accomplishing this, and I will be looking into your suggestions.
thank you for your generous feedback on this, I'm really looking forward to making some well functioning and quiet cathode switchable mods. Very useful for certain guitar tube amp tone and gain flexibilities.
Best,
Phil D.