What is the purpose of this device?
wb4cdr Clint R
Hi Clintr55. FWIW one case i have often come up against that an Add-A-Cap solves is if you do repair work or make audio projects with vacuum tubes there’s often a situation where at idle there’s an amount of Mains born hum that is more than obvious. It relates to the level of Ripple on the B+ after reification & the value/condition of the smoothing caps.
I used to unknowingly simply manually poked another another electrolytic cap onto the pins of the smoother (with the volume turned up). You would hear a loud “thunk” & then maybe a reduced ripple hum. But oneday inside an old somewhat valuable tube radio (that was not mine) i did just this & BANG… the virtually unobtainium rectifier tube arced out & went gassy pink-purple & then the power transformer started making awful buzz noises. Lucky i pulled the power plug but the transformer had been working into a dead short & the rectifier tube was wrecked… because the cap i attached was in effect a complete short in its uncharged state for just long enough to blow the rectifier into being a short for the transformer as well……
This applies to any sort of supply Linear TBH because it’s really not the best thing to go dead shorting any sort of power supply rail even though it’s for parts of a second but class it as not best practice… (and some circuits represent valuable investment in components & time so not good risking damaging it)…
I’m building the Add-A-Cap for this reason (once the dang relays arrive) but i also want to mess around with switching in a different value cathode decoupling cap in a PushPull tube amplifier outputstage circuit i’m experimenting with & this should be a much softer way of doing it…
I hope my description helps & sorry if it’s a bit long-winded.
What is the purpose of this device?
wb4cdr Clint R