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Test Equipment / Re: Choosing between entry-level 12-bit DSOs
« Last post by 2N3055 on Today at 04:37:40 pm »All 4 channels on.
Recent Posts
2
Projects, Designs, and Technical Stuff / Ebay 75mm Slide pots - Interesting Taper
« Last post by Buriedcode on Today at 04:37:17 pm »I was looking at slide pots for a prototype, so I bought up a few different models for sizing, to see which ones would fit in the enclosure I was going to use.
Whilst there's generally 45mm travel and 60mm travel, aliexpress and ebay have lots of those 75mm ones (60mm travel, but slimmer), often stereo, that are quite low profile - like the bourns PTA6043 - and was a better fit than the larger ones like Taiwan Alpha RA6020F
Examples of the cheap clones are here:
https://www.amazon.co.uk/DollaTek-Potentiometer-Double-Linear-Electronic/dp/B081JNQ7MM
I bought a pack of 5 from a random ebay seller, and one from a known "good" seller, that was mounted on a breakout board for use with Arduino/Rpi etc..
They're the perfect size for my prototype, but the taper is odd. It seems to be a "W" taper, despite all being labeled as B103 - which is usually 10k linear. The value goes from 1k to 9k (10% to 90%) between 25 and 75% of travel, which to me at least, looks like a classic W taper used in graphic EQ's. As a quick and dirty test, I used an Arduino to read the wipers with the top and bottom hooked to 5V/GND, and roughly moved it 6mm at a time to get 9 readings, and reading both tracks.
All 7 pots I have use this taper, which is annoying since it can't be used for linear control apps - even if I used a lookup table to correct its less than ideal. But it seems these are perfect for making graphic EQ's like the classic MXR 6 band EQ.
So this is just a FYI post in case others wanted to use these for control inputs and got funky results.
Whilst there's generally 45mm travel and 60mm travel, aliexpress and ebay have lots of those 75mm ones (60mm travel, but slimmer), often stereo, that are quite low profile - like the bourns PTA6043 - and was a better fit than the larger ones like Taiwan Alpha RA6020F
Examples of the cheap clones are here:
https://www.amazon.co.uk/DollaTek-Potentiometer-Double-Linear-Electronic/dp/B081JNQ7MM
I bought a pack of 5 from a random ebay seller, and one from a known "good" seller, that was mounted on a breakout board for use with Arduino/Rpi etc..
They're the perfect size for my prototype, but the taper is odd. It seems to be a "W" taper, despite all being labeled as B103 - which is usually 10k linear. The value goes from 1k to 9k (10% to 90%) between 25 and 75% of travel, which to me at least, looks like a classic W taper used in graphic EQ's. As a quick and dirty test, I used an Arduino to read the wipers with the top and bottom hooked to 5V/GND, and roughly moved it 6mm at a time to get 9 readings, and reading both tracks.
All 7 pots I have use this taper, which is annoying since it can't be used for linear control apps - even if I used a lookup table to correct its less than ideal. But it seems these are perfect for making graphic EQ's like the classic MXR 6 band EQ.
So this is just a FYI post in case others wanted to use these for control inputs and got funky results.
3
Test Equipment / Re: Multimeter selection for production testing
« Last post by KungFuJosh on Today at 04:37:11 pm »I kid you not, we found a 34465A, that was connected to a test setup, and was doing nothing.
Production people didn't even turn it on anymore. Anyway, I was kind of looking forward trying the SDM3045X/SDM3055X. I guess next time.
I guess I could trade you my SDM3045X that's upgraded to the SDM3055X-E for your 34465A. 🤔
4
Programming / Re: Linux Dependency Black Hole
« Last post by mag_therm on Today at 04:28:52 pm »Hi tatel, I don't yet have an R Pi here, I use industrial computers running on 13.8V DC , the main one is Aaeon 6651 https://www.aaeon.ai/en/product/detail/boxer-6641
No problem with capacity.
No problem with capacity.
5
Microcontrollers / Re: RIP Z80
« Last post by peter-h on Today at 04:27:20 pm »Quote
The vast majority of MCUs produced are quite narrowly tailored to a few applications they suit well.
I think most MCUs are designed for a specific automotive or other consumer application, against a customer requirement for say 10M chips annually. This is pretty obvious with some chips like Siemens ones that go into ECUs but you rarely see them generally.
But since almost nobody doing that is posting here (not allowed to, for a start) we are talking mostly about lower volume stuff.
Quote
Sticking with one maker, and their peripheral set, can be a big speed up in development work. Who cares what the core is, apart from a few special qualities like getting in and out of low power states, where a few designs excel?
We are saying the same thing, I think. A well managed company will make strategic choices in this area. They will also have direct accounts with firms like ST. They won't be searching Digikey for a suitable chip
6
Buy/Sell/Wanted / Band 1 Stereo FM Link Broadcast Warehouse TX25 Transmitter + Receiver
« Last post by kloss on Today at 04:25:40 pm »Band 1 Stereo FM Link Broadcast Warehouse TX25 Transmitter + Professionally adapted Stereo Receiver
TX25 is the full bandwidth version capable of any Band 1 broadcast channel
Receiver is XTAL controlled currently on 52.75 MHz some alternatives available from stock if required
Tested working, 1 owner from new these always gave great results
The transmitter and receiver both offer MPX Composite support
A new SBS Stereo Audio Limiter may be included free of charge on request
Any questions - let me know
£1000 Collection or shipping available
TX25 is the full bandwidth version capable of any Band 1 broadcast channel
Receiver is XTAL controlled currently on 52.75 MHz some alternatives available from stock if required
Tested working, 1 owner from new these always gave great results
The transmitter and receiver both offer MPX Composite support
A new SBS Stereo Audio Limiter may be included free of charge on request
Any questions - let me know
£1000 Collection or shipping available
7
Buy/Sell/Wanted / FS: ENI 403LA wideband RF amplifier 3 Watts 37dB 150 kHz - 300 MHz
« Last post by kloss on Today at 04:23:43 pm »ENI 403LA Class A wideband RF amplifier 3 Watts 37dB 150 kHz - 300 MHz
Tested in good working order (photos available)
Power cable fitted with IEC type connector to support variable length cables
£200 Collection or shipping available
Tested in good working order (photos available)
Power cable fitted with IEC type connector to support variable length cables
£200 Collection or shipping available
8
Beginners / Re: Bulk input caps and impedance
« Last post by Zero999 on Today at 04:22:41 pm »What's the ESR of those inductors?Now I want to try what an inductor does.
10uH torroid ... not what I expected.
470uH - more what I expected, although it appears to only delay the steep portion of the rise.
4.7mH and it's much better.... longer / smoother / lower gradient.
What's the catch?
How do they compare to a resistor of the same value?
9
Programming / Re: Linux Dependency Black Hole
« Last post by mag_therm on Today at 04:22:08 pm »Hi tatel, That is interesting.
Yes I have downloaded the firmware C files from git and have been examining them. But I dont have C IDE or debug, (And not used C for 36 years, so a lot to learn)
So thought MCUX and a devel board would give me everything including debug.
Also I have been thinking today, with the ease of uploading the firmware, and as I only need < 10 frequencies I could just build 10 firmwares each with a fixed dataset for the Si5351.
A little UI and bash to replace firmware on frequency change , and with the latest Gnuradio ( python based) which allows users to build their own DSP, could be an easy solution at least initially
Yes I have downloaded the firmware C files from git and have been examining them. But I dont have C IDE or debug, (And not used C for 36 years, so a lot to learn)
So thought MCUX and a devel board would give me everything including debug.
Also I have been thinking today, with the ease of uploading the firmware, and as I only need < 10 frequencies I could just build 10 firmwares each with a fixed dataset for the Si5351.
A little UI and bash to replace firmware on frequency change , and with the latest Gnuradio ( python based) which allows users to build their own DSP, could be an easy solution at least initially
10
Test Equipment / Re: Choosing between entry-level 12-bit DSOs
« Last post by Fungus on Today at 04:21:43 pm »1) oscilloscope is not properly BW limited, so Sinc filter is unable to reconstruct perfectly, instead of nice sine, it creates AM sine.
140MHz is below Nyquist.