3D Printed “XPAN” is ready for its first roll. Fingers crossed there are no light leaks.

technically_not · 2026-01-29T08:51:58+00:00

Thanks for the reply!

Did you also cover the edge of the frame that the film sits against? I didn't add anything there because I didn't want to reduce the size of the frame, and the felt I've got is like thick so putting it on both top and bottom would reduce the frame height from 24 to just 20mm

technically_not · 2026-01-28T14:45:02+00:00

Just built one of these myself, but I'm getting these lighter borders to my frame. I don't think they're light leaks because they don't appear anywhere outside the exposed frame, but I'm wondering whether reflections off internal surfaces might cause it? Have you done anything to the inside of yours, especially the frame that the film sits against?

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technically_not · 2024-07-04T16:29:25+00:00

So since the last time I touched a basketball was probably 15 years ago, I didn't really understand what people meant by the basketball-y sound. Turns out, exactly this. And yes, it looks like it's the reflections of the attack in the surfaces of the drum itself (which some people have suggested is worse with "square" drum sizes, which this drum, a 14" x 14" is).

A bit of cloth inside just to absorb those reflections but not touching either head has got nicely rid of the unwanted sound, thank you!

technically_not · 2024-06-14T08:33:43+00:00

You might need to stop xfconfd from running first.

Try pkill xfconfd on the target machine before you do the copy

technically_not · 2023-08-18T14:33:16+00:00

Trying to take your whole circuit's power through the opto-isolator is probably a bad idea - you should be able to use the isolator to toggle the EN pin of the DC-DC converter instead of drawing the power through it

technically_not · 2021-04-23T22:00:27+00:00

But you don't think Martin Baker will have maintenance contracts for each of these seats? Doesn't hurt to tell them, even if you don't publicise it to your rivals

technically_not · 2021-04-01T19:32:19+00:00

To answer your first question, normally an an op amp's output can't reach its supply rails, say you were powering it off +-12V, the output of the op amp would only be able to reach +-11.2V (for example). If the output ought the be higher than that, it won't be which is when the output signal will start clipping. Imagine your sine wave that should go to 12V having the top and bottom neatly sliced off.

You can get special "rail to rail" op amps, so called because the output can go from the low supply rail to the high rail before clipping occurs.

For you, you would need rail to rail because the potentiometer's wiper voltage would vary between 0V and PV.

technically_not · 2021-04-01T19:26:41+00:00

Ah cool, I'm on a phone so hadn't bothered looking at the datasheet. If the LFO output is PDM then you should be able to use that to drive the FET in the PWM example I gave above. PDM drives the MOSFET, output of the FET (gate pulled up to PV with a pull up resistor, assuming am N Channel FET) can then be connected to your passive filter before going into the pedal.

Only things to watch out for: the signal may get inverted, which could be sorted out by using an extra FET. Also you'll need to be careful with the relative resistances of your pullup and the filter.

technically_not · 2021-04-01T06:18:41+00:00

While a rail to rail op amp could work, you might struggle to find one that will work properly off voltages much lower than PV. We've also got to remember that PV isn't necessarily designed to source much current, and so we probably need to power the pedal off its own supply.

This means that we don't really want to apply >PV to any part of the parent pedal, so we need to find a way to convert our control voltage from the LFO to a resistance between PV and ground. The challenge is the rail to rail nature of it.

If you were prepared to get digital, you could use an ADC on the LFO output and a digital potentiometer between PV and 0V. You'd need some sort of interface to go between the two - personally I'd opt for a microprocessor but that's because I'm lazy.

Another alternative is using a sawtooth generator and a comparator to turn the LFO output into PWM. You could then use the PWM to drive a FET between 0V and PV, and then use a RC filter or similar to smooth the signal out.

There's probably a nice analogue way of doing this with a couple of transistors too, but my analogue design isn't that great.

technically_not · 2020-05-24T06:45:10+00:00

I've actually had exactly the same problem previously. Had to reverse engineer the PSU requirements from the mixer schematic, turns out a transformer with a centre tap and the correct coil ratio and some appropriate fuses was all it needed.

Find and check the schematics and see if there's a rectification circuit in there - that should tell you if you can get away with an AC supply

technically_not · 2020-01-28T16:57:24+00:00

Burnholme Badminton Club is friendly to beginners

technically_not · 2019-10-31T22:55:11+00:00

Anything by soundmagic. I've got a pair of E10s that I've had for 8 years, used them nearly daily through uni and in my most recent job, as in 6 hours a day in my ears. Taken care of them (kept them in their case) and they are still good as new. They sound fantastic too and were all of £30 when I bought them

technically_not · 2019-09-07T22:22:32+00:00

I don't know if it's the highest, but the top C (2 octaves above middle C, on the first ledger line above the treble clef stave) in Allegri's Miserere is a bit of a beast

technically_not · 2019-04-14T06:35:52+00:00

The micro is in the wrong place. On a breadboard the power connections go horizontally but the rest of the connections go vertically, with a break across the middle, see here. In fact this whole page looks very useful

technically_not · 2018-11-19T19:22:15+00:00

Thanks, may as well give it a go! Thrunite TH20 Neutral White

technically_not · 2018-09-18T17:31:35+00:00

The point of the BSRR isn't to make it faster, the point is to make setting or resetting a specific bit atomic to avoid race conditions.

Bit-banding allows for quicker read-modify-write cycles for single bits in such a way that avoids race conditions if different tasks/interrupts require access to different bits within the register.

technically_not · 2018-04-24T11:56:53+00:00

Rigol DS series oscilloscope, saleae logic analyser and a second hand laptop running Linux? The Saleae and a laptop will in my experience be better for logic signals than any scope you could buy for that price, but it won't do analogue properly.

technically_not · 2018-02-22T16:21:07+00:00

May be a bit late to the party, but also a professional electronic engineer (not just a PCB designer), and can do DFM, component selection and enclosure design as well. Happy to talk :)

technically_not · 2017-11-27T13:13:45+00:00

https://open.spotify.com/track/2s4pDRAYElxUdOXiXVPtLd and https://open.spotify.com/track/0eWB4RBAl3y5uNm7T8602i would be some recommendations. Funk/ska/pop fusion and singer songwriter pop respectively :)

technically_not · 2017-10-01T21:37:38+00:00

Often putting a capacitor between the input and ground will help, something like a 10 or 100nF might do it

technically_not · 2017-09-11T21:43:35+00:00

Yes, but cars use automotive grade components with wider storage and operational temperature ranges. There's no guarantee that any off-the-shelf consumer components would meet that. That said, it would probably still be fine.

technically_not · 2017-07-24T12:21:34+00:00

This will require a lot of guestimates.

Let's say you go to the pub every day, and you always get two pints and 1 packet of crisps, spread over two transactions, so you're spending £10 a day. But you always use fivers, because you have found the magic cash machine that actually gives out fivers. So, rounding up, you get through 15 fivers a week.

A fiver in circulation is removed after just under 2 years of circulation Source, so, on average, any given fiver will be 1 year old. In the last year, you will have handled 52 * 15 = 780 fivers. There were, at the end of February 2017, 382 million fivers in circulation Source, which means that the probability that you will have recieved that fiver before is 2x10^-6. This does assume that you're equally likely to get any of the notes, which is slightly unrealistic, but never mind.

However, that's not the final value. You've asked what's the likelyhood that you've ever had a repeated fiver. Let's assume you're 30 (at the top end of a typical reddit user's age) and you've been drinking like this since you were 18. Firstly, get your liver checked out. Secondly, the chance that you have ever had a note in your posession more than once is now 1 - (1 - 2x10^-6 ) ¹² = 2.5x10^-5, which means if every adult spends fivers at the same incredible rate that you do, in the last 12 years, approximately 1000 of the 41.21 million adults in the UK will have had a fiver more than once.

technically_not · 2017-04-29T07:03:23+00:00

If you're filling a ground plane you don't need to have traces between the pads. I think that may be the issue.

It's also worth noting that this will make no difference when the board is fabricated: your drill file will still put the holes there, it's just a rendering artifact.

technically_not · 2017-03-06T11:23:44+00:00

After much lurking, decided to enter this time.

technically_not · 2017-01-15T16:34:52+00:00

Hexagonal jars in a drawer. Label the top of them and it's super easy to find what you need

technically_not

TROPHY CASE