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

[merlin el mago]

Originally Posted by transistormarkj

Here's a photo of Quasimodo V.3 in operation. The 25 turn trimmer RV1 is clearly visible (dark blue box, upper right), and so is the injection capacitor C2 (light blue box, center), plugged into its socket with many pins. You also can see the three 8pin SOIC packages. It's a two layer board and if you look around you can find some vias. Frontside fill is VCC, backside fill is GND.

Many thanks to share your great work. Nice board, do you sell or do you have in mind to create a GB?

TIA
Felipe

[Mark Johnson]

Originally Posted by merlin el mago

... Nice board, do you sell or do you have in mind to create a GB?

No, I don't plan to do a Group Buy myself, but I am glad to provide all the CAD data in case somebody else wants to organize and run one. I do have about a dozen extra PCBoards and full sets of components, which I am willing to sell at my cost. After they're gone, I doubt I'll purchase-and-sell more of them; I'm not particularly interested in being a kit maker or kit seller. If someone else wants to do this, they have my blessings.

Attached are the Gerber files to make Quasimodo V.3 SMD boards, in the exact format required by PCB vendor Seeed Studio (link), which is the fab house that I used. The .zip archive also includes a Bill Of Materials (excel spreadsheet) and a schematic diagram. A photograph of this 5cm x 5cm surface mount board is attached to post #10 in this thread. KiCad screen shots show the component layer (red) and the back side layer (green). See if you can find the place where I connected the MOSFET's source pin(s) to the ground plane with six vias in parallel.

Based on the prices at the US Postal Service's website, I'm happy to sell my remaining dozen boards and/or kits-of-parts, as follows:

PCB only: {ship to USA: $5.00} {ship to MEX,CAN: $8.00} {rest of world: $14.00}

PCB + full kit of all parts: {USA: $11.00} {MEX,CAN: $16.00} {rest of world: $22.00}

Mail me a check in your local currency (trying not to injure me on the exchange rate) and I'll mail you what your ordered. Send me a PM for my address. No I don't feel like setting up a PayPal account or other internet banking convenience.

BEWARE, these are SMD boards that use SMD parts. It's very easy to lose SMD parts because they're so small; if you drop one on the floor you'll probably never find it. I don't have enough parts to send spares. So if the board uses ten SMD capacitors, I'll send ten capacitors. Not eleven, not twenty. Ten.

[merlin el mago]

I'm in for PCB + full kit but I don't have checks, could I pay by paypal?

TIA
Felipe

[coolnose]

Trying....

Mark,

more seriously, I had made the thread with your comments on the hagerman article a "sticky" , something to look into when building something "nice" the next time

Now I think I want to have one of those, kindly take me down for 1 set while I check my US contacts for the funds.

Cheers,

Max

[Mark Johnson]

Congratulations coolnose, you found the six parallel vias which connect the Nchannel power MOSFET's source terminal to the ground plane. Although there were precious few groups-of-six-vias to investigate.

Originally Posted by transistormarkj

Mail me a check in your local currency (trying not to injure me on the exchange rate) and I'll mail you what your ordered. Send me a PM for my address. No I don't feel like setting up a PayPal account or other internet banking convenience.

What did you win? How about: the privilege of running a Group Buy here after these few boards are gone, gone, gone? I've provided you the Gerbers and the BOM, all you need to do is take orders, purchase boards & parts, then ship to buyers and collect payments.

[coolnose]

My gaming addiction again...

I'll rule out for the prize offered and party my success with my fellow donkeys!

[Mark Johnson]

For those who purchased a Quasimodo V.3 PCB, here's a brief assembly guide.

• Place and solder the three 8-pin SOIC packages. See photos STEP_1 and STEP_2 for the correct orientations.
• Place and solder the three 1206 resistors. See photo STEP_3
• Place and solder the ten 1206 capacitors; they're all the same value. See photo STEP_4
• Place and solder the LED (1206 pkg) and the Schottky diode (SOT-23 pkg). See STEP_5 and STEP_6. The LED has a pair of green bars on its cathode.
• Place and solder the electrolytic capacitor. Be sure to do this before you solder any of the thru-hole components.
• Place and solder the thru-hole components. And you're done! See photo STEP_7

[pooge]

PM sent

[Karsten Sømand]

Dear Fellow DIY´ers,

In case Transistormarkj has any PCB´s and parts left I would strongly recommend that you buy this little brilliant circuit. I had the priviledge to try-out the Quasimodo to check how it worked.

It worked beautifully right from first switch-on. The Quasimodo can run on approx. 3-18 VDC so I took the easy path and connected a 9V battery.

I am not very familiar with oscilloscopes but the ringing was shown perfectly on the scope I borrowed - right as you can see in Transistormarkj´s first post. When I slowly adjusted the trimpot the ringing gradually became smaller - it almost felt like magic

If you, like me, believe in snubber circuits between your power transformer and rectifier diodes, this little circuit is a "must have". As Transistormarkj writes, it only takes approx. 3 minutes to test each winding on your transformer. It´s almost too good to be true. This is soooo cool!

In the future I can´t see myself putting a PSU together without using the Quasimodo.

BIG applause to Transistormarkj for creating this little "creature" - and for sharing it with all of us on DIY Audio

Karsten

[FdW]

Originally Posted by Karsten Sømand

Dear Fellow DIY´ers,

In case Transistormarkj has any PCB´s and parts left I would strongly recommend that you buy this little brilliant circuit. I had the priviledge to try-out the Quasimodo to check how it worked.

It worked beautifully right from first switch-on. The Quasimodo can run on approx. 3-18 VDC so I took the easy path and connected a 9V battery.

I am not very familiar with oscilloscopes but the ringing was shown perfectly on the scope I borrowed - right as you can see in Transistormarkj´s first post. When I slowly adjusted the trimpot the ringing gradually became smaller - it almost felt like magic

If you, like me, believe in snubber circuits between your power transformer and rectifier diodes, this little circuit is a "must have". As Transistormarkj writes, it only takes approx. 3 minutes to test each winding on your transformer. It´s almost too good to be true. This is soooo cool!

In the future I can´t see myself putting a PSU together without using the Quasimodo.

BIG applause to Transistormarkj for creating this little "creature" - and for sharing it with all of us on DIY Audio

Karsten

After this advertisement... I can not wait (Yes I did order)