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

[Perrow]

Also... I just placed an order with Small Bear for some other stuff... But couldn't find any of the IRF740, uf4004 or the inductor available... I think I searched Tayda and they didn't have them either...

Tayda stocks the IRF740, but not the UF4004 yet (I've emailed them and they say they'll have them ASAP). Until then Futurlec is your friend.

[MetalUpYerEye]

Sweet! Futurlec has everything i'll need and I already have the caps for this... I just won 2 ebay auctions as well... One for a NOS 6112 and the other for a NOS 6021... Both are RCA and even come with the original boxes...  And for only $2.50 each with $6.50 shipping...  They're the same seller so i'm gonna see if he'll combine shipping and save me a couple more bucks... Not much but would still be nice...

It makes me sick to think that i've paid $11 for 2 tubes when I could have bought a lot of 10 tubes for $25... I just don't need 10 of each of these... If my build works out I might do 2 more (one for my Brother, one for my Dad...) Time permitting of course...

I'm still planning on building the Pentaboost as well... Maybe as a permanent front end boost in my Superfly... We'll have to see. I was really planning on building the Pentaboost first so get my feet wet in submini's but the 6112 and 6021 auctions kind of jumped up on me...

I asked before but didn't get a response... Maybe its somewhere in this thread... How come you chose to use 6111wa instead of 6021 on most of your builds, FC?

[bluesman1218]

Best source for NOS Tubes in the US is Vacuum Tubes, Inc. in Orlando, FL. Jim knows his tubes, has a huge inventory and is very reasonably priced. I have been buying from him for about 6 years, now. Tell him Steve from VintageToneUSA, in Orlando sent you.  http://www.vacuumtubesinc.com/Products/VacuumTubes/NewTubes1603to8950.aspx

[MetalUpYerEye]

Those tubes seem a bit overpriced... $10 for a 6111 and $22 for a 6112... $8 for a 6021 but they have the fabled 7327 for $10 each!

I just got an email from the ebay seller I won my auctions at. He's combined my shipping so $2.50 per tube plus $3.50 shipping = $8.50 for both tubes.  Not bad for buying single units I guess.

[bluesman1218]

Those tubes seem a bit overpriced... $10 for a 6111 and $22 for a 6112... $8 for a 6021 but they have the fabled 7327 for $10 each!

I just got an email from the ebay seller I won my auctions at. He's combined my shipping so $2.50 per tube plus $3.50 shipping = $8.50 for both tubes.  Not bad for buying single units I guess.

Depends what you're buying/your requirements are. I build for myself and for sale. I need reliability and a supplier who stands behind his/her product. If it's strictly a hobby, that may not be so important. Yes, that is good pricing and many good deal are out there. Bottom line is, Jim keeps his inventory current and absolutely stands behind his products. The fact the he's 20 mins. from my door is nice, too!

[MetalUpYerEye]

I noticed this in a video I saw earlier... A nixie style power supply module, fully built, 1.2-18v input with a 150-200v adjustable output... For $13 shipped. I might just do one of these instead of building the Nixie, although i'm setting myself up for problems by not following the layout... Is anyone making PCB's for the Superfly?

http://www.tayloredge.com/storefront/SmartNixie/PSU/index.html

[zambo]

the nixie on this thread is better and puts out more ma and voltage i belive. You may want to stick with it. My 2 cents.

[frequencycentral]

How come you chose to use 6111wa instead of 6021 on most of your builds, FC?

Easier to find, and cheaper. 

[MetalUpYerEye]

How come you chose to use 6111wa instead of 6021 on most of your builds, FC?

Easier to find, and cheaper. 

Ahh ok. I was able to find both but since you're probably looking for large quantities of them 6111 is probably easier to find...

the nixie on this thread is better and puts out more ma and voltage i belive. You may want to stick with it. My 2 cents.

They have a link to a nixie kit comparison chart on that website... It has the nixie used in this build on there and says that its has Iout Max of 10mA and Pout Watts are 1.8w. The smaller module has an Iout of 68mA and Pout of 11.5w...

I want to explore adding a second power tube to this thing once its built... How much current are these circuits drawing as is?

[Perrow]

I'm soldering this one up right now (well not right NOW, I'm at work) on perfboard, but while here at work I looked up something on the schematic and suddenly realised I had the tubes mixed up 

So there'll be some desoldering and resoldering tonight 

BTW: Didn't use the IRF740 but rather an 18N50, the on resistance is 0.22R (18N50) instead of 0.48R (IRF740), meaning lots less heat

Also, got a lesson in temperature coefficients. Measured the tube heaters with my Ohm-meter and got about 6R and thought "f**k, that's 2A, that can't be right". But then when I connected my variable power supply and slowly turned up the amp regulator they, of course, heated up and the current stopped around 0.3A.

[iccaros]

I'm soldering this one up right now (well not right NOW, I'm at work) on perfboard, but while here at work I looked up something on the schematic and suddenly realised I had the tubes mixed up 

So there'll be some desoldering and resoldering tonight 

BTW: Didn't use the IRF740 but rather an 18N50, the on resistance is 0.22R (18N50) instead of 0.48R (IRF740), meaning lots less heat

Also, got a lesson in temperature coefficients. Measured the tube heaters with my Ohm-meter and got about 6R and thought "f**k, that's 2A, that can't be right". But then when I connected my variable power supply and slowly turned up the amp regulator they, of course, heated up and the current stopped around 0.3A.

you can calculate the heater resistance from the data sheet. For example the 6111 says .3  do 6.3/.3 = 21ohms    or 1.89 watts  if you need to add a resistor for the heaters for any reason, like to use a 12v heater supply.

[frequencycentral]

BTW: Didn't use the IRF740 but rather an 18N50, the on resistance is 0.22R (18N50) instead of 0.48R (IRF740), meaning lots less heat

Interesting! I await your results with anticipation!

[MetalUpYerEye]

I have parts on the way for this build as well. I'm going to pre-make a passive Baxandall and FMV tone stack to switch between the two and see what I like better.

I ordered all the same part numbers as the schematic though... I ordered everything from Futurlec, who have everything in stock that this project needs, minus the tubes and xfmr.

Come to think of it... I ordered the 100uh inductor from Futurlec too, but it looks much different from the one you've shown in pictures FC... Anyone tried it with that inductor?

[Perrow]

I had no idea, but among the 21 tubes I recieved when I bought "20 pieces of 6112 tubes" from ebay where one (1) 6021 tube!

And with an amazing stroke of luck my fingers selected that one when I opened the drawer and picked what I thought were a 6112, so it turns out I can test my amp without resoldering 

[Perrow]

BTW: Didn't use the IRF740 but rather an 18N50, the on resistance is 0.22R (18N50) instead of 0.48R (IRF740), meaning lots less heat

Interesting! I await your results with anticipation!

Well, I have tested just the SMPS part without heatsink and after 10-20 seconds the 18N50 is barely warm to the touch 

[Perrow]

Hey FC, am I correct thinking every resistor is 1/4 watt? Seems to my eyes (and when it comes to tubes they're not that good) that R1 (440 ohm) is taking a lot of beating for a 1/4 watt resistor.

[user]

Umm noob question. How do u get 185 volts out of a 9v battery? 

[frequencycentral]

Umm noob question. How do u get 185 volts out of a 9v battery? 

http://www.diystompboxes.com/smfforum/index.php?topic=74088.msg613311#msg613311

[Perrow]

Hey FC, am I correct thinking every resistor is 1/4 watt? Seems to my eyes (and when it comes to tubes they're not that good) that R1 (440 ohm) is taking a lot of beating for a 1/4 watt resistor.

Never mind, made a model in LTSpice and got the answer 

Dissipation: 27.0901 mW

The answer is therefore that 1/4 watt resistor for R1 works great, and anybody wondering why should really investigate/study voltage dividers

[Perrow]

BTW: Didn't use the IRF740 but rather an 18N50, the on resistance is 0.22R (18N50) instead of 0.48R (IRF740), meaning lots less heat

Interesting! I await your results with anticipation!

It does produce very little heat, but I bought my inductor from Futurlec (their power inductor) and can't get the HV over 100V (with tubes, without I've had no problem dialing in up to 200V), so I'm going to order some inductors from Mouser (as well as some IRF740, just to be sure).

If someone has Mouser part numbers for known working inductors I'd be grateful.

If anyone else had problems getting the voltage up (with load) and solved the problem I'd like to hear how.

As for how little heat the 18N50 produce, I've had the amp working for about five minutes and it was just warm to the touch (no heatsink).