Simple, no-math transformer snubber using Quasimodo test-jig

Parts are so affordable, I will try your suggestion. I appreciate the help!

I find the price of parts amazing. If you can do an A to B comparison please post the results. I will order some of the orginal mosfets and do the same. Just curious what, if any difference we see in the results.

I tested a couple of dual voltage transformers from Antek today. I ran 4 tests and the measured subber resistance varied between 49 and 51 ohms. I was impressed with the consistency.
 
Hi sonidos,

That big Infineon 60R360P7 would likely work nominally. But it's a poor substitute in a couple ways at least:

- it has Vdss rating of 650V !! Think an order of magnitude smaller: 40 - 60V is plenty

- the pinout is the same, but the pin spacing is 4.25mm; your PCB is 2.54mm

- the On resistance spec is 360 mOhms; the original is 9 milli-Ohms

PM me your address and I'll comp you some; I picked up a batch on closeout a while back.

merlin el mago,

For a 150 VAC secondary, 9k1 sounds like a pretty high value. Perhaps it is very low current (10 - 25mA) secondary, or your MOSFET is 'weak', say a few hundred milli-ohms, and not therefore *ringing the bell* very hard?

What is the DC resistance of the secondary? (And sorry I didn't think to ask that earlier ..:eek:))

Cheers
 
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Rick, thanks for the offer! I was too much the eager beaver to get a mosfet on my next order with Mouser that I missed that the pin spacing was totally off, as well as this is a high voltage part. I'll send you my personal info later today. If I bump into a suitable sub, I'll post it here for future reference.
 

6L6

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David-

A oscilloscope is only as good as it’s trigger, and I can’t imagine it’s got anything other than something very basic and crude for $99.

It could be decent, it could very well work perfectly. However, if it doesn’t, a scope that does work just got $99 more expensive as the price of this gets rolled into the right tool.
 
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David-

A oscilloscope is only as good as it’s trigger, and I can’t imagine it’s got anything other than something very basic and crude for $99.

It could be decent, it could very well work perfectly. However, if it doesn’t, a scope that does work just got $99 more expensive as the price of this gets rolled into the right tool.

Okay, something like this,

SDS1052DL+ | Siglent

?

Thanks,

David.
 
Both of those pieces look pretty capable -- and under $300 US. But the Siglent has a 5x higher sampling rate and 10 times the sample depth; and for a few dollars less, better name included.

6L6, Your advice is spot on, as usual. So many budget 'scopes have had such awful, unstable trigger circuits that they're almost unusable. Gotta wonder, though (and that's all I can do;), since I have no first-hand experience with DSOs), on a machine that's steadily digitizing the incoming signal stream, won't trigger design be just fitting a suitable algorithm, instead of an entire separate circuit? At least that's how it floats around in my brain ..

That little pocket job is a real cutie for $100, though, eh? And the spec sheet says it can operate at up to 500°C -- hard to beat that!!

Regards
 
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free boards

I have 2 test jig boards available. They are the Seed v4 through hole file boards in Green, ENIG and 2 oz copper.

They will land to you at no cost. Limit one per customer. Left over from my buy.
US only as I do not have time to do customs stuff.

PM me if interested and provide ship to address.

Just trying to give a little something back.

Don
 
I have snubber installed. How can I check if it works well on the destination place? IMG_20201124_222609.jpg
 
Hello, i am going to build one i just wanted to know if my shopping list looks okey, i just dont want to buy anything that wont work :) sometime i wasent able to buy the same as in the BOM. i hope that someone out there can check my list :) have a nice day all

TLC555IP - IC, TIMER, 555, PDIP8

MCP1407-E/P - Dual MOSFET Driver, 4,5V-18V , 6A ut, 40ns DIP-8
IRLB8748PBF - MOSFET, N 30 V, 40 A, 0.0038 ohm, TO-220AB,

VISHAY - BFC237011154 -0.15 µF, 63 V,
EPCOS - B32529C0103J000 -10000 pF, 63 V
KEMET - R82EC1100DQ50J -1000 pF, 100 V
K104K15X7RF53L2 - 0.1 µF, 50 V
EEUFR1J221LB - 220 µF, 63 V, FR
3296W-1-102LF - Trimpot, -1 kohm 25 Turn

78B04ST - DIP / SIP
PR01000108200JA100 - 820 ohm, PR01 Series, 1 W, ± 5%, Axiell, 350 V
MF25 4K7 - 4.7 kohm, 250 mW, ± 1%, Axiell, 250 V
MF25 39K - 39 kohm, 250 mW, ± 1%, Axiell, 250 V
MF25 10K - 10 kohm, , 250 mW, ± 1%, Axiell, 250 V
F25 2K - 2 kohm, , 250 mW, ± 1%, Axiell, 250 V
1N5819-E3/54 - Schottky 40 V, 1 A, DO-41 (DO-204AL), 2 Stift, 600 mV
803-87-044-10-001101
 
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Have you had a chance to study the .zip archive files attached to post #1 of this thread? There's one for the thru-hole version of Quasimodo ("V.4") and there's another for the surface mount version of Quasimodo ("V.3").

I think you'll discover that the .zip archive files include a Bill Of Materials ("BOM"). Screen capture image below.

_
 

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Hello, yes i have, it is from that file that i have chosen the components, i got leds and the cable connections, so i dident add them. The thing is that som part wasent in stock so i can get it or i needed to buy alot of them so it got to expensive (min order on some parts was 10, even om half expensive parts) so i might have gotten a more expensive part sens i only had to order one. The resistors is probobly no problem with, the ICs and some components at the top of my list that i am not as sure, i just want to be 100% sure that the parts will work �� the total is up to about 37$ in parts without PCB or veroboard, and i need to buy for at least 20$ Or els i cant shop there and the shipping (inside my contry) is 10$ �� so i dont want to make anothere order :)
 
Where are you shopping that your total was 37$? :eek:

DigiKey has the IRFB8748, single quantity, for 89 cents.

The resistors could be 5% and maybe save a few cents.

Which ones were the parts that you had to buy 10 of? Other members on this forum would probably buy some of your extras.

If one of your parts is a dud, there's a decent chance someone else on here would be willing to share a substitute (so that you wouldn't have to commit another order).

Granted, I know absolutely nothing about international shipping, or end-user fees, or other obstacles you may face. But you have access to a ton of wisdom and willing help on this forum -- go ahead a pull the trigger.

Cheers
 
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