My thought was to go with an LCRCRC filter before the zeners with the help of the inverter keeping the line at a steady voltage - +- 1 volt and that is over a long time - most of the time it is very steady. 124 volts and it stays there.
The only time consumer and that is not that big of a deal is to get the output of each raw supply just about 123 volts.
Worth a try and a good test to find out if I can be hear it at all. No complaints if it cannot be heard! I w2ill stick with the zeners as regulators and get on to some other avenue of obsession.
Thanks for your counsel and wisdom, Ben Mah.
Rick, in the other thread, you mentioned about the inverter you have to generate pure AC. If you were thinking of not using a transformer and connecting the output of the inverter directly to the board, I would strongly advise against it. The transformer provides isolation and safety from the mains and it should be used. Sorry if I misread you but better to be doubly cautious.
No, I will be using a transformer. I have no idea how to do that! I like making things simple but as the old saw goes NO simpler! Planning on using a 2 x 22 volts secondary wired in series and then a voltage doubler rectifier and then the CLCRCRC filter - the last section may be omitted to get the voltage right. And if my experiment with zener noise proves to be much ado about nothing ...
I got the filter wrong in the first post - from what I can see a choke input filter does not work with a voltage doubler as one would expect.
The inverter does many interesting things but that might be a step too far.
Nonetheless, I appreciate the concern and advice.
I got the filter wrong in the first post - from what I can see a choke input filter does not work with a voltage doubler as one would expect.
The inverter does many interesting things but that might be a step too far.
Nonetheless, I appreciate the concern and advice.
Closing the GB this Sunday. We are up to 30 PCBs, which is great.
A number of people have asked about the gain FET, STP30N10F7, which has been labelled obsolete. Digikey has 300 of them right now. But they are sold out everywhere else. I have a small stash of about 100 and can supply those to whoever needs them. We'll figure it out at the time of payment.
Once the GB closes, I'll place the order and PM folks who have expressed an interest with details.
Link to GB spreadsheet.
A number of people have asked about the gain FET, STP30N10F7, which has been labelled obsolete. Digikey has 300 of them right now. But they are sold out everywhere else. I have a small stash of about 100 and can supply those to whoever needs them. We'll figure it out at the time of payment.
Once the GB closes, I'll place the order and PM folks who have expressed an interest with details.
Link to GB spreadsheet.
Got my semiconductors on order for the line stage - got what I need to turn my Singing Bushes into TDV with THF51 - will use on hand LUNDAHL LL2733s until Slagle comes up with a choke - so the question is - when would you expect the boards to get to you and for you to find the time to send them out? Just trying to plan not to worry or rush you.
I got my ten from DK also.
Cannot wait to see what you have in mind.
ra7 - sorry to hear you spent the night in an ER - glad the kid is OK.
Well, the plan was to order boards last night but that didn’t work out. Hopefully tonight. Should be 2-3 weeks from that point for me to get the PCBs. Then a few days for me to get all of it out to everyone.
I can’t wait to see what you do with them! Your input has been invaluable, as always!
Haven’t ordered boards yet, so still open.Hope I was'nt too late, as always
I can look that up later. I would guess between $10-$15.
The circuit shown in posts #1 and #2 are very similar to an amp design I did called UNSET. SET is a common abbreviation in the vacuum tube audio world for Single Ended Triode. UN because there are no triodes in the design but the composite tube / mosfet curves are very triode like. The first picture shows a set of curves hand traced from a tube / mosfet pair. The UNSET is a two stage amp design with a voltage gain stage and a power amp stage. The major difference is just the size of the parts. The gain stage looks just like the circuit in post#1 except that the gain device is a small signal vacuum tube. Resistive loaded and CCS loaded (post #2 with a single IXTP10M45S) versions have been built. High power (20+ WPC) amps need the CCS to get enough overall voltage gain. The second stage uses a larger P fet on the heatsink and a fat TV sweep tube for the gain device. The load is the OPT. This board runs on 350 to 650 volts. The UNSET board is seen in the second and third pictures. The CCS chip is on the little heat sink.
I made this comment back in post #71:
In post #87 I called the tubeless UNSET the FETSET. In post#88 I was asked:
This thing keeps circulating around in my brain and popping up every so often, so I keep thinking about it. I even dug out an old breadboard but decided that it was too much work to make it into what I want. Now that there are some ready made boards it should be easy to build a FETSET. It would be possible, and probably easier to eliminate the OPT, but I have some decent Toroidy 600 ohm OPT's capable of 20 to 30 watts that I got for a cathode follower output stage, some 650 volt SiC J-fets, and a heat sink big enough for two boards, so I'll have to put them all together. Real tube amps have OPT's, right? I'll know more once I have the boards in hand. The question is whether to build a stereo preamp and a stereo power amp, or a pair of two stage pre / power amp boards.
