well, it becomes monotonic now - Pa is again my Nemesis
embraced his FW pcb form factor, then reworked it to mostly complies with DiyA UMS, and now I'm stuck
while him using less and less space for parts , I'm using more and more and simply lost space for Green Diodes
though, thinking to include a clause - each of my kits, must have 20mm Green LED on front of amp, when finished
naah, make it 50mm Dia
Got some SITs... now have built a Frankentracer... fiddled with Franky tonight on some LU tiny JFETs on old Tek scope.
Used Michael's SIT Modeller on curves that came with the Tokin THF-51S, so have spice model of SITs in hand.
This app is so cool. Thanks Michael. 😎
Hmm... what to do? L'amp with inductor looks promising on first stab sim.... wait for Papa N-ch SIT part 2? Now I see SissySIT rev 3... so many possibilities....
What have I gotten myself into?
Used Michael's SIT Modeller on curves that came with the Tokin THF-51S, so have spice model of SITs in hand.
This app is so cool. Thanks Michael. 😎
Hmm... what to do? L'amp with inductor looks promising on first stab sim.... wait for Papa N-ch SIT part 2? Now I see SissySIT rev 3... so many possibilities....
What have I gotten myself into?
Planning on a Frankentracer myself for my THF-51Ss and other toys. And I too am sinking into something that seems very fun and scary at the same time. What a beautiful world...
Waiting for further delivery from Tomo. I also have the feeling I am sinking into something very funny for a newbie. Can wait to listen to this amp with my Tannoy 15".
By the way, these THF-51S purchases are perfectly in tune with all this carbon neutrality thing. Just look at the shipping route from Tokyo to Paris : JAPAN > CHINA > THAILAND > INDIA > GERMANY > FRANCE
Tokyo, JP 2021/03/30 19:35 in transit
Narita, JP 2021/03/30 21:32 in transit
Shenzhen, CN 2021/03/31 01:36 in transit
Shenzhen, CN 2021/03/31 05:11 in transit
Samutprakarn, TH 2021/03/31 07:01 in transit
Samutprakarn, TH 2021/03/31 08:36 in transit
New Delhi, IN 2021/03/31 11:04 in transit
New Delhi, IN 2021/03/31 18:10 pending
New Delhi, IN 2021/04/02 21:35 in transit
Koeln, DE 2021/04/03 00:11 in transit
Koeln, DE 2021/04/06 03:33 in transit
Roissy Charles de Gaulle, FR 2021/04/06 04:47 in transit
Corbeil Essonnes, FR 2021/04/07 04:46 in transit
Feeling a bit shameful, isn't it ??
By the way, these THF-51S purchases are perfectly in tune with all this carbon neutrality thing. Just look at the shipping route from Tokyo to Paris : JAPAN > CHINA > THAILAND > INDIA > GERMANY > FRANCE
Tokyo, JP 2021/03/30 19:35 in transit
Narita, JP 2021/03/30 21:32 in transit
Shenzhen, CN 2021/03/31 01:36 in transit
Shenzhen, CN 2021/03/31 05:11 in transit
Samutprakarn, TH 2021/03/31 07:01 in transit
Samutprakarn, TH 2021/03/31 08:36 in transit
New Delhi, IN 2021/03/31 11:04 in transit
New Delhi, IN 2021/03/31 18:10 pending
New Delhi, IN 2021/04/02 21:35 in transit
Koeln, DE 2021/04/03 00:11 in transit
Koeln, DE 2021/04/06 03:33 in transit
Roissy Charles de Gaulle, FR 2021/04/06 04:47 in transit
Corbeil Essonnes, FR 2021/04/07 04:46 in transit
Feeling a bit shameful, isn't it ??
If you are feeling shameful about it, you are in luck today! I will take the devices off your hands for free thereby removing any guilt you are feeling.
I know, I know... it is a truly generous offer by me and how could you possibly impose upon a stranger in the community? I assure you that it is not an imposition and I would dispose of the items you mail to me in an environmentally friendly manner befitting of the components.
Anyone else feeling guilt from their finished SS class A/vacuum tube/class D audio gear, partially populated boards, devices, heatsinks, chassis, and/or components diy or commercial offerings... well, this offer is open to you all too.
😀
I tracked mine and it literally went, Tokyo Narita, Vancouver, Toronto Pearson, drove down the highway to front doorstep.
I know, I know... it is a truly generous offer by me and how could you possibly impose upon a stranger in the community? I assure you that it is not an imposition and I would dispose of the items you mail to me in an environmentally friendly manner befitting of the components.
Anyone else feeling guilt from their finished SS class A/vacuum tube/class D audio gear, partially populated boards, devices, heatsinks, chassis, and/or components diy or commercial offerings... well, this offer is open to you all too.
😀
I tracked mine and it literally went, Tokyo Narita, Vancouver, Toronto Pearson, drove down the highway to front doorstep.
I will be surprised if the package is allowed into India. Cody sent me Nelson's Giveaway, it made it all the way from the US to New Delhi. It was returned from there and is somewhere back on its way to the original sender. I guess its all Covid restrictions.
I blame it on ZM. I can't get away from listening to my SissySIT V1. It's my drug of choice. I have a couple pairs of THF51S for the next projects, Singing Bush, NP design.....
I just received four unmatched THF-51S from Japan and now I would like to see if I can match them. However, I have never done this so far and before I start to destroy them by accident I would like to ask you some silly questions. 🙂
There is the V_gs tracing approach with a constant DC voltage across drain and source described by Zen Mod here:
SissySIT
This is quite clear to me. I have a heatsink and an amplifier PSU with 24 V. I just need to get the 10k pot and some alligator clips to go ahead.
1. I do not have a variac. Is it mandatory to use a variac in the Frankentracer? Or is this just a nice safety feature because it allows you to increase and decrease V_ds according to the parts that you are testing?
2. I only have some 200 VA transformers either with two 18 V or two 27 V secondaries. Using a 18 V secondary would give a max. voltage of about 25 V. I this ok to be used in the Frankentracer for the THF-51S? Or maybe I could even use the 27 V transformer?
3. The light bulbs in the Frankentracer with 266W to 300 W @ 115 V are hard to source in Europe. Instead, could I use two 500 W @ 230 V lamps in parallel?
4. In the Frankentracer video from Michael Rothacher it is said that the light bulb could also be replaced with a resistor. In this case what resistance is needed? I guess the power rating has to be quite high due to the high currents.
Thanks in advance for your help
Regards
Stephan
There is the V_gs tracing approach with a constant DC voltage across drain and source described by Zen Mod here:
SissySIT
This is quite clear to me. I have a heatsink and an amplifier PSU with 24 V. I just need to get the 10k pot and some alligator clips to go ahead.
But I also have a scope with XY-mode so it would be nice to built the Frankentracer. For this I have the following questions.
2. I only have some 200 VA transformers either with two 18 V or two 27 V secondaries. Using a 18 V secondary would give a max. voltage of about 25 V. I this ok to be used in the Frankentracer for the THF-51S? Or maybe I could even use the 27 V transformer?
3. The light bulbs in the Frankentracer with 266W to 300 W @ 115 V are hard to source in Europe. Instead, could I use two 500 W @ 230 V lamps in parallel?
4. In the Frankentracer video from Michael Rothacher it is said that the light bulb could also be replaced with a resistor. In this case what resistance is needed? I guess the power rating has to be quite high due to the high currents.
Thanks in advance for your help
Regards
Stephan
1. Frankentracer work only with variac
2. In the schematic secondaires are 25 V but 27V secondairy is OK just drop 2V (put into circuit some passive components for this)
3. You can use two bulbs in parallel
4. 25 Ohms /300Watts or more power resistor
2. In the schematic secondaires are 25 V but 27V secondairy is OK just drop 2V (put into circuit some passive components for this)
3. You can use two bulbs in parallel
4. 25 Ohms /300Watts or more power resistor
Merci beaucoup for the answer, Soundhappy!
As I do not have a variac the Frankentracer is then not an option for me.
By the way is there an explanation why the variac in front of the normal transformer is mandatory? To me this setup is just two transfomers in series and I do not see any difference to just one transformer as long as you get the right voltage after the transformer.
As I do not have a variac the Frankentracer is then not an option for me.
By the way is there an explanation why the variac in front of the normal transformer is mandatory? To me this setup is just two transfomers in series and I do not see any difference to just one transformer as long as you get the right voltage after the transformer.
@ Mgb1965
Extract from L'Amp article about variac with similar curve tracer schematic
Source: http://blog.audiomaker.tech/pdf/lamp part one.pdf
At the biggining MR adjust to 45V on the oscilloscope screen.
Do you have Lab Stabilized PSU ?
Extract from L'Amp article about variac with similar curve tracer schematic
Source: http://blog.audiomaker.tech/pdf/lamp part one.pdf
At the biggining MR adjust to 45V on the oscilloscope screen.
Do you have Lab Stabilized PSU ?
Attachments
These are precious parts, so I would want to have the ability to bring things up slowly rather than flipping a switch and crossing my fingers. 🙂
Strictly speaking, a curve tracer isn't needed to match parts for Vgs if you only have a DC supply.
Strictly speaking, a curve tracer isn't needed to match parts for Vgs if you only have a DC supply.
Hello Michael,
Thanks for the clarification. So the variac is rather a safety feature for the tested device to bring the voltage slowly up and down and depending on the tested device you can also adjust the voltage swing which might be helpful if you want to test different transistor types.
I also watched your video about the Frankentracer which by the way I found very interesting and helpful. Just one further question on this:
In fact, in the video you are swichting on the variac which beforehand was adjusted to 100% lines voltages. I thought that in this case the variac is of no use and you could have directly connected the 25VAC transformator to mains voltage with a switch or do I missunderstand something?
Concerning the matching of my THF-51S I will then stay with the Vgs tracing with the DC voltage from my 24 V PSU.
By the way: I built a pair of your MoFos with the Hammond 193V. I like it very much!
Thanks for this design. Looking forward to built a follower with the THF-51S.
Regards Stephan
Thanks for the clarification. So the variac is rather a safety feature for the tested device to bring the voltage slowly up and down and depending on the tested device you can also adjust the voltage swing which might be helpful if you want to test different transistor types.
I also watched your video about the Frankentracer which by the way I found very interesting and helpful. Just one further question on this:
In fact, in the video you are swichting on the variac which beforehand was adjusted to 100% lines voltages. I thought that in this case the variac is of no use and you could have directly connected the 25VAC transformator to mains voltage with a switch or do I missunderstand something?
Concerning the matching of my THF-51S I will then stay with the Vgs tracing with the DC voltage from my 24 V PSU.
By the way: I built a pair of your MoFos with the Hammond 193V. I like it very much!
Thanks for this design. Looking forward to built a follower with the THF-51S. Regards Stephan
I am still playing with the testing for the 2sk182es and THF51s and it is clear that
you can have parts with the same Vgs figure and not have a performance match.
Not to worry, but there's a little more work to do.
you can have parts with the same Vgs figure and not have a performance match.
Not to worry, but there's a little more work to do.
and