Trem-O-Nator Vactrol?

[tdvt]

Only semi-tube related as I have been fooling with a SS LFO to bias-vary pre-amp tubes for trem.

The SS LFO works great, basically a standard Fender design with a LDN150 subbed in for the tube.

But to get things running, I needed to add a follower & used the same MOSFET.  I can get nice trem but the follower circuit seems to need more work as I have burned up a few. So I thought I would also try the Trem-O-Nator vactrol section to manipulate the signal while I was fooling with all of it.


The question arises as to what people been using for the Vactrol, both make & model?



Sluckey's drawing on his site says VTL5C1, but I found a drawing here listing a VTL5C3, plus I recall further discussion of some particular brands not working correctly.

[sluckey]

I used the attached data sheet to choose the VTL5C1. It worked very well so I never tried any others. The 5C3 is cheap and easier to find the Vactec Vactrol brand so get some and experiment.

Look at page 41 for a quick comparison chart.

[tdvt]

Thanks, I wasn't sure how particular the choice of the 5C1 was.

I will see what I can find, try out the 5C3 too.

Looking at all the specs on the chart you linked, I am guessing that the "On"Ω  & "Off"Ω are the first criteria, but what kind of current rating is suitable?

[sluckey]

The current rating is for the LED. More current means brighter LED which means lower LDR resistance. The circuit operates at about 1mA or less. So, pay attention to the on resistance for the 1mA input current. Lower resistance is better. Also pay attention to the turn on/turn off response times. Fast is better.