Iron Pumpkin(s) and other smaller vegetable animals, Tips 'n' Tricks thread

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Well, origin thread is here : Iron Pumpkin(s) and other smaller vegetable animals

If nothing else, read at least first several posts on linked page , to grasp enough info about concept itself.

This one having two purposes :

-placing all necessary info about final iteration,

-trying to layout clearer picture of what's fuss about,

-with edits of this first post - making comprehensive list of tips and tricks and funny fine details , and answering on any clever or dumb question you'll possibly have ......either here or further in thread

(3 purposes then , not two :rofl: )

edit at 22.05.2020. short how-to-do for Iron Pumpkin SE, referencing to post #2:

do not connect buffer output to Turtle

maximize trimpot R36 (measure across R39 to confirm max value)

R37 position is irrelevant for now

if you're sure that you connected everything properly, just power it on

set positive and negative rails to +/-12Vdc , with trimpots R9 and R10

power off, place DVMdc crocs across R34, power On then fiddle with R36 to set 20mV across R34, then fiddle with R37 to set 0mV DC offset at output


do everything the same with other channel, connect outputs of buffers to Turtle, enjoy
 
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Perfect place for Iron Pumpkin SE set of informative files

OK ....... you already read Origin Thread , so you know that Iron Pumpkin SE package is comprised of two mono pcbs , and one Iron Turtle module , where two Metglas-cored AVCs are sandwiching one pcb , with plenty of Takamisawa relays ...... operated by rotary switch ..... there is a wide flat cable between switch pcbs and Turtle

Channel pcbs contains relay input selector, Good Gemini bipolar shunt regs and extra funny zillion small JFets buffer.

Selector Takamisawa relays are operated with second rotary switch - Lorlin 2section/6 position ( shorting or MBB) , so two tinier flat cables are going from switch to channel pcbs ( one cable per channel)

set of pics :
 

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Perfect place for Iron Pumpkin set of informative files

So call it either Iron Pumpkin Bal or just Iron Pumpkin - it is not having SE in name .....

Also made of two mono channel pcbs , difference to SE being one more buffer, simply because it is needed for additional phase

Iron Turtle for balanced - each Metglas cored AVC having two bobbins (one per phase) , connected in pure differential mode (contrary to some other AVCs around , using one xformer per phase , so no possibility of intrinsic Supersymmetric operation of differential iron

Also - each AVC is having own relay pcb , but two channels are stacked vertically , practically taking same space as SE Turtle

same switches and flat cables as for SE iteration

additional relay (6-th) on channel pcb is for case that you want to use arbitrary number of SE inputs ; when SE input is chosen , additional relay is energized , so connection between negative buffer output and negative AVC coil is cut , ensuring that non-modulated negative buffer is not acting as virtual GND for its coil ...... which is now modulated from his twin - positive coil , thus we still have full balanced/differential output

set of schm/pics:

(last one - proper input pads labeling - for guys recently getting my pcbs with old, still buggered silkscreen ; sorry guys - it's already corrected for next batch of pcbs)
 

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Iron Turtle set of schmtcs

oh yeah ... this one was tricky one ..... but am I satisfied with final result ...... you can bet :)

may I remind you ..... 24 position rotary switches , even if made by Most Beautiful Chinese Virgins only in Full Moon nights - each one is dissasembled , greased (some old and fancy graphite based grease , good for Stagecoaches and my switches) and assembled , thus expecting at least 15 years of proper use ....... two sections are connected in parallel
 

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Should I post some fresh measurements ....

OK , my buddy Zeljkor ( as known on Baby DiyA) recently acquired AP1 Dual Domain ( or whatever) , and he was interested in having fun with Iron Pumpkin SE

as soon I manage to make another balanced , we'll arrange AP session for that one , too

so - set of measurements follows :
 

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Iron Turtle set to 8db gain, 2Vrms in

did I said this position is emergency one ?

observe that I'm using exactly this one constantly in my workshop , needing some gain for Papa's Koan F4 ....... and it sings fabulously :clown:
 

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Now zillion of pics about assembly of channel pcbs

I'm really getting tired of upload routine :devily:

anyway - pcbs in question were for balanced Iron Pumpkin ; will post detailed instructions for setting both SE and balanced in forst post of thread later ...... for know you know the drill - parts smallest in height first , then taller ones , then taller ones ........
 

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