"Superfly" - submini tube version of Doug H's Firefly

[iccaros]

Quick question... how come you're using taps 2 & 5 on the output transformer but the Firefly build guide uses 2 & 4... i'm connecting this to an 8ohm speaker to test it.

On to that PCB layout I did... got a board kindly donated by Markeebee today (Thanks Mark!) and i'm gunna say not to build it, unless you don't mind offboard wiring. I'm gunna use and verify it (or not as the case may be) but mounting on the back of the PCB just takes up too much depth in an standard enclosure so i'll redesign it with the tubes the right way round this time and pots on the same side.

Thankfullly my enclosure is deeper than most so I can get away with it, but it's an odd enclosure.

Hopefully all being well, i'll have an (out the box at least) 12AX7 & U7 firefly verified by tommorow night!

I'll wait, as I just was ready to etch your board this weekend, as I have three days off.
I was wondering if you would mind, I got some 6N2P-EV, which are close to a 12ax7 but require 6.3 voltes between the 4 and 5 pin instead of 12. I think in yours you put 4 and 5 together and 9 to ground, but if you could make 4 to a jummper, I could try it with these tubes
Thanks

Also use the ratio that gives 22K. I have used it @ 10K, but 22K @ that voltage is what the math shows..
I use http://www.musicalpowersupplies.com/ OT5PP, I buy them in lots of 2 for $51 shipped.

[Scruffie]

Not sure I follow you... I don't mind doing it but if you read the thread, I had enough trouble with heater wiring already so you might need to make it a little clearer for me 

Yes i'd wait, even if you do build this version it'd be best I verified it before you wasted your time.

What you could do is wire the pots on the component side of the board, but just stick the middle leg in and flip the outside lugs with wires to the alternate hole so sorta semi-board mounted The tube socket should be okay on the back depth wise, if you can solder it in that way. This may be an idea if you want to build this soon as i'm not sure when i'll have time to do the new layout, could be tommorow, could be 3 months.

[iccaros]

I saw your heater issues
there are two ways to wire two tubes for 12volts one is in series of each other using the parallel wiring in the tube (the top half of the drawing)
The other being in parallel using the tubes series internal wiring, the second half of the drawing.


But looking at these if you did the second half then modifing like this


would allow me to jumper between ping 5 of tube one and pin 4 of the next.

This would allow the use of more tubes types. 

[Scruffie]

Tell you what i'll do... i'll add 4 pads on the tracks between the tubes so you can cut them and jumper how you like. That way anyone building with standard tubes doesn't have to add jumpers but it's still simple for people that want to use other tubes.

[iccaros]

cool, thanks

[Scruffie]

No worries 

Now does anyone have an answer to my transformer taps question?

[iccaros]

use the 22K:8 ohm ratio..

I modified my answer above, but you might have missed it.
Think of the transformer as  a plate resister, which helps control how much current can pass, at 22K you keep current with in 80% of max dissipation 

[Scruffie]

Ahhh I did miss that yeah, 2 & 4 it is then!

One other thing... I only have a 10k Trimmer, what values should I change the resistors in the voltage divider to?

[Scruffie]

Right... well i'm glad I tested it without the tubes and transformer.

So first off I was just getting 12V, couldn't work out why... and I still don't know, came back to the computer to check i'd got everything right and I had...

Plugged it back in and the voltage was fluctuating around so I stuck my meter on to the High voltage setting... and it settled around 500V, pretty sure I heard a hissing sound.

So... now i've put the trim back the other way, the voltage is fluctuating around 100-200V Have I just killed my high voltage caps, they look okay, it all looks fine, could it be a low battery in the meter causing weird readings? Or do I need to replace all the Charge Pump components.

Edit: It seems to charge up and shoot up to around 250V then drop back down again in incriments over a few seconds to 100Vish and repeat this pattern, tried it with a second multimeter and it was much the same.

Is this poor layout (may well be, I did try and keep to the MAX1771 article reccomendations) burnt out parts, or is it one of the few value subs I made - 47uF instead of 100uF Cap off the 12V, assumed this was just filtering and a 10k Trim instead of 5k... I also used one of the smaller inductors due to the bigger one not fitting the layout properly... also the 1M5 resistor is just a regular carbon film resistor, shouldn't it be high voltage? Wasn't noted so on Ricks schematic.

Oh and for anyone that builds one of these... don't have a few drinks get curious as to what that voltage feels like  it feels Exactly how you think it'll feel.

[iccaros]

my superfly does the same thing once I get over 120 volts, my RMS meter shows one voltage but it has a meter under the numbers that keep jumping.

I think I have a bad part, maybe a cap somewhere, but have not found it yet.

[Scruffie]

my superfly does the same thing once I get over 120 volts, my RMS meter shows one voltage but it has a meter under the numbers that keep jumping.

I think I have a bad part, maybe a cap somewhere, but have not found it yet.

This wont settle on any voltage.

I did realise that i'd left the rest of the circuit hooked up though with no tubes or transformer, hopefully after I lift the resistor joining it, things will settle down... or not as the case may be.

If not I assume bad layout or buggered caps... I get a steady 12V up untill the diode, after the diode, the voltage is all over the place.

[Perrow]

My dmm won't measure the smps correctly, I think the high frequency messes it up. My analog meter does the trick. Old tech not so easily fooled by a measly 555

[Scruffie]

My dmm won't measure the smps correctly, I think the high frequency messes it up. My analog meter does the trick. Old tech not so easily fooled by a measly 555

Oh really? This may well be the issue!

Well of course i'm using a MAX1771 here but my DMM is a cheapie one (thing doesn't even have the right impeadance to measure V.Refs with out weird readings alot of the time).

I don't have anything else to test it with though... and I can't just guess what voltage i'm giving the tubes really... dilemma.

[iccaros]

Success bad output cap on the power supply.. no more oscillation, will put pics and sound tomorrow.. 

[iccaros]

My dmm won't measure the smps correctly, I think the high frequency messes it up. My analog meter does the trick. Old tech not so easily fooled by a measly 555

I have a Fluke that has no issues, but it is True RMS..
My Radio Shack has no real issues, floats 1 and 10's volts but the hundreds are stable, so I can see that I am between 170 and 180v

my $1.98 Harbor Freight just looks at me..  

[lopsided]

hey,

I am lying with a broken leg, planning to try this build, going through the schems and parts.
Do you think it is a good idea to build this on vero? I don't etch and am too impatient for perf, so I am doing most of my builds on vero. I am thinking of two separate boards: one 555 power and one  amp section.
I am not really concerned to make it small (my first layout sketches go about 9x20 each board and I am OK with the size) but I've seen here mentioned that the circuit could be sensitive to parts a trace placing. So I am not sure if the long and wide strips of the vero wouldn't  cause any problems. What do you think?

 

[iccaros]

hey,

I am lying with a broken leg, planning to try this build, going through the schems and parts.
Do you think it is a good idea to build this on vero? I don't etch and am too impatient for perf, so I am doing most of my builds on vero. I am thinking of two separate boards: one 555 power and one  amp section.
I am not really concerned to make it small (my first layout sketches go about 9x20 each board and I am OK with the size) but I've seen here mentioned that the circuit could be sensitive to parts a trace placing. So I am not sure if the long and wide strips of the vero wouldn't  cause any problems. What do you think?

 

Rick did an outstanding job with vero, look through the tread and all of Ricks threads, as he does an outstanding job of documenting his build

[Scruffie]

hey,

I am lying with a broken leg, planning to try this build, going through the schems and parts.
Do you think it is a good idea to build this on vero? I don't etch and am too impatient for perf, so I am doing most of my builds on vero. I am thinking of two separate boards: one 555 power and one  amp section.
I am not really concerned to make it small (my first layout sketches go about 9x20 each board and I am OK with the size) but I've seen here mentioned that the circuit could be sensitive to parts a trace placing. So I am not sure if the long and wide strips of the vero wouldn't  cause any problems. What do you think?

 

Rick did an outstanding job with vero, look through the tread and all of Ricks threads, as he does an outstanding job of documenting his build

Rick made Perf layouts, not Vero.

Sorry to hear the leg's busted! Urmm... I dunno, depends on your layout skills as to building it on vero, no reason it shouldn't work though.

[Perrow]

hey,

I am lying with a broken leg, planning to try this build, going through the schems and parts.
Do you think it is a good idea to build this on vero? I don't etch and am too impatient for perf, so I am doing most of my builds on vero. I am thinking of two separate boards: one 555 power and one  amp section.
I am not really concerned to make it small (my first layout sketches go about 9x20 each board and I am OK with the size) but I've seen here mentioned that the circuit could be sensitive to parts a trace placing. So I am not sure if the long and wide strips of the vero wouldn't  cause any problems. What do you think?

Start here: Nixie SMPS Vero

Then do a design for the "missing" parts.

Edit: Break a leg, no wait, you already did that

[lopsided]

Start here: Nixie SMPS Vero

Then do a design for the "missing" parts.

Edit: Break a leg, no wait, you already did that

thanks guys and thanks for the link. I often forget about our galleries here.
I guess I'll start with the SMPS and see if I can make it work. And then continue with the amp.

The leg is killing me. It doesn't hurt much but I have to stay at my parents' (I live on fourth floor with no elevator) until they allow me to step on the leg. I basically just took my guitar and notebook but left the amp and DIY stuff at my place. So it's all planing future builds for me now.