If you're nervous that your pot readings are not repeatable, one thing you can do is purchase 3 more pots. Run each of the 4 pots in Quasimodo, dial up the waveform shape you like, and then measure the resistance of each one. If one measured value is screwy and the other three are tightly grouped, you know which pot to throw into the fireplace. I like to recommend 25-turn trimmers because they offer lots of granularity. Futurlec sells them for $0.90 qty=1 and other places carry them too.
Another thing you can do (and should do!) is to run Quasimodo a second time. The first time you run it with a potentiometer, and you choose a snubber network (Cx, Cs, Rs). Next, you order parts from your supplier. When those parts arrive, plug them into Quasimodo and run it again. Yes you can plug a fixed resistor's leads into the trimpot's socket. Now you've got a fixed resistor, not a trimpot; when you run it in Quasimodo, if it doesn't give the waveshape you like: WOW! You just dodged a bullet! You discovered that you were about to use a snubber that doesn't actually work the way you prefer. (On the other hand, if your Cx, Cs, Rs does give the waveshape you like, you've seen that with your own eyes. You can sleep comfortably.)
Another thing you can do (and should do!) is to run Quasimodo a second time. The first time you run it with a potentiometer, and you choose a snubber network (Cx, Cs, Rs). Next, you order parts from your supplier. When those parts arrive, plug them into Quasimodo and run it again. Yes you can plug a fixed resistor's leads into the trimpot's socket. Now you've got a fixed resistor, not a trimpot; when you run it in Quasimodo, if it doesn't give the waveshape you like: WOW! You just dodged a bullet! You discovered that you were about to use a snubber that doesn't actually work the way you prefer. (On the other hand, if your Cx, Cs, Rs does give the waveshape you like, you've seen that with your own eyes. You can sleep comfortably.)
Yes, I have been using various components to see what happens since I am in the learning phase I am making numerous attempts. I have long to go before drudgery sets in so it's fun for the moment.
I am considering a 10 turn pot not a single instead of the trimmer. I figure for ease of removal and re-insertion I would go ahead and short the leads and use the appropriate "holes" on the board header.
If I was nuts I would get a TEXAS COMPONENTS trimmer which are steady as rocks but I do not want to have to wait for it. Plus they are thirty dollars.
I am looking at a surplus HELIPOT which I have heard are good. AS many snubbers as I need to make I do not want to worry about the trimmer. It sells for ten dollars.
If I may ask again: is thee anything critical about the 1k value? My assumption is a 10 turn 500K would give me all of the resolution I would need IF the value is unimportant.
Thanks,
I am considering a 10 turn pot not a single instead of the trimmer. I figure for ease of removal and re-insertion I would go ahead and short the leads and use the appropriate "holes" on the board header.
If I was nuts I would get a TEXAS COMPONENTS trimmer which are steady as rocks but I do not want to have to wait for it. Plus they are thirty dollars.
I am looking at a surplus HELIPOT which I have heard are good. AS many snubbers as I need to make I do not want to worry about the trimmer. It sells for ten dollars.
If I may ask again: is thee anything critical about the 1k value? My assumption is a 10 turn 500K would give me all of the resolution I would need IF the value is unimportant.
Thanks,
V4 Through Hole Boards Available to AU & NZ members for $AU3.20 + postage
Hi All,
Many, Many thank to Mark for all his hard work and for making this freely available to the diyAudio community and specially for all the excellent support, it's very much appreciated!
I've had an all to easy, event free experience with Seeed Studio making 10 of "V4 Through Hole" boards for a total, inc. postage to North Sydney Australia, of $AU32.10. I simply sent the provided Seeed files and got back the boards which look OK, see attached scan. I chose Seeed's cheapest option; the following cut and pasted from my Seeed completed orders page:
PCB Dimension - 5cm Max*10cm Max
Layer - 2
PCB Thickness - 1.6mm
PCB Qty. - 10
PCB Color - Green
Surface Finish - Hasl
Copper Weight - 1oz.
Panelized PCBs - 1
The boards are (99 x 46 x 1.6)mm and weight 14.6g each.
I have six of the above boards spare which I'm making available, at my cost, to Australians and New Zealand diyAudio members for $AU3.20 per board - limit one each - plus postage of $AU1.00 to Australia or $AU1.85 to New Zealand. Payment by paypal in Australian Dollars, AUD, prior to posting.
So that's totals of:
* $AU4.20 - including regular letter postage to anywhere in Australia
* $AU5.05 - including regular letter postage to anywhere in New Zealand
I'll post back here that all the boards are spoken for when I've received six firm PMs from diyAudio members in Australia or New Zealand. If there is little interest then people can have more than one board each and postage will be the same for multiple boards.
If any of the first six don't go through then I'll post back here that they are again available.
This is the first time I've done this so please people, let me know if I'm missing something or likely to get myself into trouble. 🙂
Thanks again Mark!
Cheers!
Rob
Hi All,
Many, Many thank to Mark for all his hard work and for making this freely available to the diyAudio community and specially for all the excellent support, it's very much appreciated!
I've had an all to easy, event free experience with Seeed Studio making 10 of "V4 Through Hole" boards for a total, inc. postage to North Sydney Australia, of $AU32.10. I simply sent the provided Seeed files and got back the boards which look OK, see attached scan. I chose Seeed's cheapest option; the following cut and pasted from my Seeed completed orders page:
PCB Dimension - 5cm Max*10cm Max
Layer - 2
PCB Thickness - 1.6mm
PCB Qty. - 10
PCB Color - Green
Surface Finish - Hasl
Copper Weight - 1oz.
Panelized PCBs - 1
The boards are (99 x 46 x 1.6)mm and weight 14.6g each.
I have six of the above boards spare which I'm making available, at my cost, to Australians and New Zealand diyAudio members for $AU3.20 per board - limit one each - plus postage of $AU1.00 to Australia or $AU1.85 to New Zealand. Payment by paypal in Australian Dollars, AUD, prior to posting.
So that's totals of:
* $AU4.20 - including regular letter postage to anywhere in Australia
* $AU5.05 - including regular letter postage to anywhere in New Zealand
I'll post back here that all the boards are spoken for when I've received six firm PMs from diyAudio members in Australia or New Zealand. If there is little interest then people can have more than one board each and postage will be the same for multiple boards.
If any of the first six don't go through then I'll post back here that they are again available.
This is the first time I've done this so please people, let me know if I'm missing something or likely to get myself into trouble. 🙂
Thanks again Mark!
Cheers!
Rob
Attachments
Excellent job, kissmurphy! Congratulations on your success. And thank you for sharing with everyone, just how quick and easy it is to buy PCBs today. Two clicks on a webpage to upload the zip archive of Gerber manufacturing data files, then type in your shipping address, payment info, and wham! PCBs by return post, very quickly.
One thing I learned when giving away and selling PCBs+kits here on diyAudio, is that some cautious people prefer to buy quantity=2 if the price is low. It's inexpensive insurance in case they screw up the first attempt. I gently recommend that if someone asks to buy two, you allow it. And if you run out of boards before demand dries up: maybe another OZ/NZ member will step up and order yet another batch of PCBs! As you have proven: it's fun, it's easy, it's not expensive, it's good for the soul.
BTW there's a full bill of materials, including recommended substitute part numbers, attached to post#1 in this thread. Post#103 shows a build guide.
One thing I learned when giving away and selling PCBs+kits here on diyAudio, is that some cautious people prefer to buy quantity=2 if the price is low. It's inexpensive insurance in case they screw up the first attempt. I gently recommend that if someone asks to buy two, you allow it. And if you run out of boards before demand dries up: maybe another OZ/NZ member will step up and order yet another batch of PCBs! As you have proven: it's fun, it's easy, it's not expensive, it's good for the soul.
BTW there's a full bill of materials, including recommended substitute part numbers, attached to post#1 in this thread. Post#103 shows a build guide.
Thanks for the encouragement + New maximum of two boards per member
Hi People,
Thanks, and your very welcome!
Yes, your right, I'm actually keeping two for myself and the first request that came in was also for two boards. If people want two I'm happy to comply for the same postage. Thanks for the tip. 🙂
I hope so, the idea behind limiting it to one was to help as many people as possible. Yes, it is good for the soul, they've proven that helping others contributes to your happiness. 🙂
Excellent, you've made it all super easy for us all. Thanks again Mark for all the time your putting into this.
Cheers!
Rob
Hi People,
Thanks, and your very welcome!
Yes, your right, I'm actually keeping two for myself and the first request that came in was also for two boards. If people want two I'm happy to comply for the same postage. Thanks for the tip. 🙂
I hope so, the idea behind limiting it to one was to help as many people as possible. Yes, it is good for the soul, they've proven that helping others contributes to your happiness. 🙂
Excellent, you've made it all super easy for us all. Thanks again Mark for all the time your putting into this.
Cheers!
Rob
Have used QUASIMODO with the ten turn pots and it works very well.
Found I could leave the multimeter connected and read what resistance I was using. Made no difference with the leads removed so I figure it is benign. Good for this beginner to see the relationship.
Looking around for a rectifier to use in the SALAS phono. I had used those rectifiers I had mentioned in the SIT1 post but thought I would look for something with a smaller voltage drop.
I found this, I have no intention of using it but thought you might find Figure #8 interesting. I am assuming their test is similar to QUAIMODO simply due to the other rectifier's ringing.
http://www.onsemi.com/pub_link/Collateral/MBRS4201P-D.PDF
Seems to me that the new rectifier would certainly not gain anything from snubbing. Looks to me that is so "over-snubbed" as to make me think this would not be a good rectifier for audio.
Thought you might find it interesting.
Found I could leave the multimeter connected and read what resistance I was using. Made no difference with the leads removed so I figure it is benign. Good for this beginner to see the relationship.
Looking around for a rectifier to use in the SALAS phono. I had used those rectifiers I had mentioned in the SIT1 post but thought I would look for something with a smaller voltage drop.
I found this, I have no intention of using it but thought you might find Figure #8 interesting. I am assuming their test is similar to QUAIMODO simply due to the other rectifier's ringing.
http://www.onsemi.com/pub_link/Collateral/MBRS4201P-D.PDF
Seems to me that the new rectifier would certainly not gain anything from snubbing. Looks to me that is so "over-snubbed" as to make me think this would not be a good rectifier for audio.
Thought you might find it interesting.
Rick, thanks for that datasheet.
I note the spec value of "maximum instantaneous reverse current - Ir" is 1mA (fig 4 confirms the two values for 200Vr and 25°C & 150°C)
Yet the final diagram of If vs time. I can see that reducing a 1A forward current to zero induces a reverse current of about 1.2A when Vr=30V
Surely the inclusion of "instantaneous" is incorrect? It is the continuous reverse current that has a maximum of 1mA @ 25°C when Vr=200Vdc
The instantaneous reverse current is more than one thousand times worse than the continuous reverse current !
I note the spec value of "maximum instantaneous reverse current - Ir" is 1mA (fig 4 confirms the two values for 200Vr and 25°C & 150°C)
Yet the final diagram of If vs time. I can see that reducing a 1A forward current to zero induces a reverse current of about 1.2A when Vr=30V
Surely the inclusion of "instantaneous" is incorrect? It is the continuous reverse current that has a maximum of 1mA @ 25°C when Vr=200Vdc
The instantaneous reverse current is more than one thousand times worse than the continuous reverse current !
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These devices are usually measured with low duty-cycle pulses to avoid self heating which would spoil the junction temperature parameter.
I would guess that's why the spec sheet guy wrote 'instantaneous' (see also forward current specs).
The reverse current peak in Fig.8 is mostly capacitive current, not leakage current.
The maximum reverse current rating is a flag for the designer not to rely on typical values in circuits were reverse current is a design factor. Reverse current is a very hard to control process parameter, so they decided to spec the max on the safe side, it seems.
I would guess that's why the spec sheet guy wrote 'instantaneous' (see also forward current specs).
The reverse current peak in Fig.8 is mostly capacitive current, not leakage current.
The maximum reverse current rating is a flag for the designer not to rely on typical values in circuits were reverse current is a design factor. Reverse current is a very hard to control process parameter, so they decided to spec the max on the safe side, it seems.
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I just received two Quasimodo V4 boards from Rob, (kissmurphy), perfect packaging, prompt postage.
Nice design/layout, perfect quality boards, thank you Rob and MJ.
Dan.
Nice design/layout, perfect quality boards, thank you Rob and MJ.
Dan.
Instead of removing the variable trimpot to determine the resistance, I just added a switch to connect the trimpot to an external meter - saves 'stuffing about' with the pot.
I prefer the belt and suspenders and elastic waistband approach. I prefer to use soft recovery rectifiers, and at the same time, also include a CRC snubber across the transformer secondary, tuned for zeta >= 1.0. The schematic of my RingNot PSU board (below) shows a specific example of this design approach. It costs a little more to buy soft recovery rectifiers and to also buy 2 capacitors and 1 resistor for the snubber; but I don't mind the expense. I'm not trying to build commercial products to hit a price point.
The ON Semi MBRS4201 features a specification that I like very much: extremely low Vfwd compared to other soft recovery rectifiers. Thus it will self-heat much less than other soft recovery rectifiers. However I am not sure I'm completely comfortable with a SMD diode and no heatsink, at least, not for RMS currents above 1 ampere or so.
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The ON Semi MBRS4201 features a specification that I like very much: extremely low Vfwd compared to other soft recovery rectifiers. Thus it will self-heat much less than other soft recovery rectifiers. However I am not sure I'm completely comfortable with a SMD diode and no heatsink, at least, not for RMS currents above 1 ampere or so.
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Attachments
So would you predict that rectifier to be on the sluggish side?
My conceptual view is it would be better to have a "lively" rectifier and tune out the resonance?
OR is that curve typical of fast recovery rectifiers?
My conceptual view is it would be better to have a "lively" rectifier and tune out the resonance?
OR is that curve typical of fast recovery rectifiers?
Two boards delivered safely, four still available.
Hi Dan,
Great, thanks for confirming they arrived safely and I'm glad you like them. Mark and seeed diserve the credit for the boards themselves.
I have four left if anybody is interested, max of two per person, see my previous posts.
Regards,
Rob
Hi Dan,
Great, thanks for confirming they arrived safely and I'm glad you like them. Mark and seeed diserve the credit for the boards themselves.
I have four left if anybody is interested, max of two per person, see my previous posts.
Regards,
Rob
Referring to post #58
Is this the latest set of gerber fiels for the Quasimodo TH version ?.
Thanks
Here in Europe, Euro Circuits have quoted me 68 Euro for 2 boards or 83 Euro for 5 boards.
Anyone know of a cheaper PCB board maker in Europe ?.
Thanks
Twenty PCBs for 38 to 45 Euros, shipping to Germany. Twenty PCBs, not 2 or 5. See attached image; click to view fullsize.
To obtain price quotes for other destinations, visit that website and ask for France (or Iceland, or Portugal, Greece, etc.). Presto, 45 seconds later you get a quote.
v.4 thru-hole PCB is 48mm x 98mm, 2 sided, silkscreen on both sides, default trace width, default drill size.
Very latest and greatest Gerbers & all else, attached to post #1 at the top of this thread.
_
To obtain price quotes for other destinations, visit that website and ask for France (or Iceland, or Portugal, Greece, etc.). Presto, 45 seconds later you get a quote.
v.4 thru-hole PCB is 48mm x 98mm, 2 sided, silkscreen on both sides, default trace width, default drill size.
Very latest and greatest Gerbers & all else, attached to post #1 at the top of this thread.
_
Attachments
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Great.
Many thanks Mark, for your reply, and for sharing the design in the first place.
I don't need 20 PCBs so I will happily sell them on to members of the forum at cost + postage (once I have the boards).
Finally got a copy of the LINEAR AUDIO article and was surprised that the diode you used in the GAINCLONE power supply was not among the preferred.
It does have the same "softness factor" as those expensive diodes I am using in the amplifiers. I got some of those to use in the phono amp and buffers.
Since I am not an expert I gladly take the advice of trusted experts! I suspect I will be pleased with them.
It does have the same "softness factor" as those expensive diodes I am using in the amplifiers. I got some of those to use in the phono amp and buffers.
Since I am not an expert I gladly take the advice of trusted experts! I suspect I will be pleased with them.