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Group Build: Dynafet


luvdunhill

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yup, looks right. I'm confused why these heat sinks won't work? The 2SC3381 is "BCE ECB" so just flip one of the devices and things should work, just like with the JFETs. I hope I didn't miss anything.

No that's what I'm saying. The layouts as already done would not work for the heatsinks because one device of each pair needs to be flipped.

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No that's what I'm saying. The layouts as already done would not work for the heatsinks because one device of each pair needs to be flipped.

If the layouts will work for the dual parts, they will work for the heat sinks as they were made to retrofit a pair of single devices into the dual package. I suppose I'm confused here? I'll look at it again tonite, as I gotta run.

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If the layouts will work for the dual parts, they will work for the heat sinks as they were made to retrofit a pair of single devices into the dual package. I suppose I'm confused here? I'll look at it again tonite, as I gotta run.

They won't work for the duals (one device is flipped). They were laid out for singles. Singles in place of the duals have the flat of one device pointing 180 degrees from the flat of the other device (like the HS).

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doesn't look like it to me ... He just used that footprint on the silk. Notice the connections between the 2SC3381 and 2SK389.

Uhhh, yes you're right :-[

Let me return to my confusion.

So, you guys actually like diptrace? I took a look at it this morning, and :confused:, at least with the schematic editor.

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Uhhh, yes you're right :-[

Let me return to my confusion.

So, you guys actually like diptrace? I took a look at it this morning, and :confused:, at least with the schematic editor.

j4cbo (Jacob Potter) is now a member of Head-Case :)

If we invite him into the Casino..., I'm sure he will jump right in to help with board design issues

]

Why is this in the Casino????

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I imagine it's here to keep the general masses from polluting the thread too much and keep things H-C oriented.

Speaking of pollution... I'm dumb as a box of sand and don't understand any of this technical stuff. What is the most basic and simple SE option for one of these? Two boards and a PSU or what.. :confused: I read the answers to Torpedos post and I'm still baffled.

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I imagine it's here to keep the general masses from polluting the thread too much and keep things H-C oriented.

Speaking of pollution... I'm dumb as a box of sand and don't understand any of this technical stuff. What is the most basic and simple SE option for one of these? Two boards and a PSU or what.. :confused: I read the answers to Torpedos post and I'm still baffled.

two boards and a PSU will give you great SE sound.

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I imagine it's here to keep the general masses from polluting the thread too much and keep things H-C oriented.

Speaking of pollution... I'm dumb as a box of sand and don't understand any of this technical stuff. What is the most basic and simple SE option for one of these? Two boards and a PSU or what.. :confused: I read the answers to Torpedos post and I'm still baffled.

Yes. 2 boards and I guess a sigma22 PSU. 80VA 2x30V trafo (or 30-0-30 or 60Vct). If you are going to do it in a single box, then trafo should be shielded if toroid; split bobbin or r-core should be fine as well. Additional sundry items such as case, volume pot, jacks, wiring, etc.

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Yes. 2 boards and I guess a sigma22 PSU. 80VA 2x30V trafo (or 30-0-30 or 60Vct). If you are going to do it in a single box, then trafo should be shielded if toroid; split bobbin or r-core should be fine as well. Additional sundry items such as case, volume pot, jacks, wiring, etc.

When talking Sigma 22, are we saying a standard 3-board Beta 22 PSU will do the job? If so I may already have that covered.. If that is the case then I'd just need two boards and ancillary pieces.

Is this correct or am I being a dumbass again and missing the obvious?

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When talking Sigma 22, are we saying a standard 3-board Beta 22 PSU will do the job? If so I may already have that covered.. If that is the case then I'd just need two boards and ancillary pieces.

Is this correct or am I being a dumbass again and missing the obvious?

If you have one of these The σ22 Regulated Power Supply you are covered.

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Awesome, I have a Beta 22 coming so theoretically I could get two boards and a switch between the beta and Dynafet, maybe even in the same case as long as heat is well managed and carefully laid out. Now that could be a possibility providing 2 board isn't overly expensive for my meagre funds.

Time to go back and look at BoMs :)

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Hi, folks :cool:

Is it still the plan to go with the same Dynahi-like board layout? I'm thinking that I'd actually like to play around with the design a bit here; in particular, using surface mount for resistors when possible, to keep the size down and signal paths short. I know a lot of DIY folks have a phobia of surface mount, but IMHO it's actually easier than through hole in quantity, and makes the end result a lot prettier.

If I were designing a power supply for this sort of thing, I'd throw in a microcontroller, dot-matrix VFD, all sorts of voltage / current / temperature monitoring, and potentially dynamic bias adjustment - but that's just me. :P

Is everyone set on using 2SJ76/2SK213 (or J79 and K216) output devices?

edit: Fortunately I've still got my old board files around. Just barely within the size limits of EAGLE's free version.

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Is everyone set on using 2SJ76/2SK213 (or J79 and K216) output devices?

yup, also check out the heat sinks towards the start of the thread for the desired orientation for the input JFETs and VAS BJTs. Also, I vote for adding 0.2" pitch footprint for the resistors... in fact, what about a combo 0.2" and SMD footprint? I think that would be sweet.

Edited by luvdunhill
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Awesome, I have a Beta 22 coming so theoretically I could get two boards and a switch between the beta and Dynafet, maybe even in the same case as long as heat is well managed and carefully laid out.

Just a word of caution - that might be a bad idea, unless you are very careful. The S22 power supply does not like being connected to an amp while/after it is turned on. The amp appears as a dead short, and since there is no output current limiting you can blow the S22.

You would have to be very disciplined to make sure that the power was off before you switched from one amp the the other.

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yup, also check out the heat sinks towards the start of the thread for the desired orientation for the input JFETs and VAS BJTs. Also, I vote for adding 0.2" pitch footprint for the resistors... in fact, what about a combo 0.2" and SMD footprint? I think that would be sweet.

Yep, I saw that. Very nice heatsink design.

0.2" for those very small through-hole resistors? Seems reasonable. I'll whip something up this weekend...

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Yep, I saw that. Very nice heatsink design.

0.2" for those very small through-hole resistors? Seems reasonable. I'll whip something up this weekend...

If we can get the same output transistor hole pattern and mounting bolt pattern as the Dynahi boards, several of us could plug n play the new boards into existing dynahi amps, or at least reuse the dynahi heatsinks....

this is not paramount, but nice to have if feasible.

Jacob,

Also, have you scanned the old headwize DynaFet thread to make sure all the 'catches' made there have been incorporated?

Cheers

Pete

And welcome aboard Jacob :D

There are probably several characters that you recognize from other places here as well.

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Hi, folks :cool:

Is it still the plan to go with the same Dynahi-like board layout? I'm thinking that I'd actually like to play around with the design a bit here; in particular, using surface mount for resistors when possible, to keep the size down and signal paths short. I know a lot of DIY folks have a phobia of surface mount, but IMHO it's actually easier than through hole in quantity, and makes the end result a lot prettier.

If I were designing a power supply for this sort of thing, I'd throw in a microcontroller, dot-matrix VFD, all sorts of voltage / current / temperature monitoring, and potentially dynamic bias adjustment - but that's just me. :P

Is everyone set on using 2SJ76/2SK213 (or J79 and K216) output devices?

edit: Fortunately I've still got my old board files around. Just barely within the size limits of EAGLE's free version.

How about distributed node architecture - rail caps close to the power output devices w/bypass caps for even faster response.

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I got some preliminary pricing from Imagineering for a board run at 25, 50 and 100 pieces, with an option to double it at about half price. I included electrical testing just to see how much it was, but probably would not recommend it. It was never done for the dynalo/dynahi board runs.

25 boards = $8.32 + $4 tooling = $12.32

50 boards = $5.43 + $2 tooling = $7.43

100 boards = $3.98 + $1 tooling = $4.98

plus shipping and delivery to each person.

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Edited by Pars
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