Recent Posts

1

Repair / Re: Hakko 850 Rework station - power switch wiring help

« Last post by alanep on Today at 12:07:55 pm »

Hello Exxor,

I don't have the schematic but I did check out my Hakko 850. I disconnected VH5 & took a photo. The pins are actually numbered on the white connector case as per the numbering in the photo. I buzzed them out to the front power switch. Because the switch NC/NO contacts could interfere with the buzzing out, I temporarily disconnected the wires from the switch (to be sure).

The numbering shown in the switch photo are their corresponding VH5 pins.

A few other notes:

VH5 pin 4 goes to the fuse holder. VH5 pin 5 isn't used.
The power switch LHS has wires going elsewhere - I didn't check them out as you only wanted those specific to connector VH5.

I hope this helps.

2

Beginners / Re: Lab PSU for learners

« Last post by TERRA Operative on Today at 11:59:27 am »

The E3631A is a great PSU if you can get it (as with the rest in that range), I wouldn't hesitate.

I also have the Siglent you mention that I hacked to the better model (I made a guide on doing the upgrade here on the forum somewhere). I haven't used it in anger yet, but it works great so far.
The newer ones have had revisions to their design that fixes problems in the earlier units.

3

Mechanical & Automation Engineering / Re: High density connector troubleshooting

« Last post by mendip_discovery on Today at 11:57:38 am »

Markerpen? Paint it on, offer it up and see which gets marked. Then clean with IPA afterwards.

4

Computers / Re: Format a 256GB pendrive with FAT32 using a windows 10 pc

« Last post by Mechatrommer on Today at 11:56:27 am »

here's why it ended up with 32GB, from the horses mouth; https://youtu.be/bikbJPI-7Kg?si=hWx5hdDppKhhQecj&t=365

am i listening this correct? if i do, OP should be thankful to M$... maybe he forgot who invented exFAT? (or FAT in general) how not thankful of him?



i just formatted my 64GB (i dont have larger) pendrive with FAT32 (archaic FAT) its charming, so the claim is bollock unless you want to keep repartitioning drives with command line...

5

Projects, Designs, and Technical Stuff / How to run some I2C sensors outdoors over longer distances (5-10m)?

« Last post by victorhooi on Today at 11:51:59 am »

Hi,

I'm looking to run some environmental sensors outdoors to monitor some greenhouses.

I'm using the Mycodo software, which runs on a Raspberry Pi. However, the sensors would be 5-10m from the Raspberry Pi.

The sensors are from Atlas Scientific - some of them communicate over I2C - e.g.:

• Humidity Sensor
• Color Sensor

Atlas Scientific also sell an extension cable, but they mention that the length is limited to a max of 3.6 meters. (My understanding is that i2c was never designed for long distances).

I know that Sparkfun make some I2C differential extenders, and you can use this with copper Ethernet cable to run i2c over longer distances. They have:

• QwiicBus Endpoint - which converts 4-wire I2C into differential signalling over Ethernet cable
• QwiicBus Midpoint - which lets you extend the range (I probably won't need this part for the 5-10m), but then also apparently lets you insert a sensor at that point - so you get a bus-style topology.

I've made a diagram for how I think this could work:



Questions:

• Would this approach work, or is there something I've missed here? Is it OK to have all of those sensors will share the same I2C bus, and I'll be able to communicate with each one separately (assuming they all have different I2C addresses)?
• Will there be a benefit to using shielded Ethernet cable, or would normal UTP cable work fine here?
• Is there a cheaper way of doing this? I've realised that the Sparkfun Qwiibus boards aren't cheap - $22 for each midpoint, and I'd need one for each sensor. Is there a cheaper way of doing this somehow?
• All of this will be outdoors, and exposed to the elements. Do you have any suggestions for a lightweight and compact way to waterproof each of the Qwiicbus Endpoint and Midpoint boards, and also the wires that go into them? (I was thinking plastic project boxes, with cable glands - but that's going to get super unwieldy and clunky on my tiny balcony).

6

Beginners / Re: Lab PSU for learners

« Last post by Wallace Gasiewicz on Today at 11:35:06 am »

I think it is hard to develop your own variable PS. Not so hard with a small one output PS.   Best to go with a triple PS, sounds like that is what you need. There is a reason they make these things. Like You, many folks require pos and neg supplies and a TTL PS.   
You could save some money and buy an older triple PS, but then you would have to verify the volt output with a multimeter, which you do not want to do. I don't blame you. It is another time consuming step.

That Keysight PS looks wonderful, wish I had one.

7

Beginners / Re: Lab PSU for learners

« Last post by AcdNrg on Today at 11:30:44 am »

If you want linear:

Linear is said to be better suited for the audio related work I focus on, but that´s just hearsay for me. Will look into those options, thank you!

8

Beginners / Re: Lab PSU for learners

« Last post by AcdNrg on Today at 11:29:40 am »

Buddy of mine mentioned an HP E3631A which is collecting dust at his workbench.

https://www.keysight.com/us/en/product/E3631A/80w-triple-output-power-supply-6v-5a--25v-1a.html

Any opinion on that thing?

It´s old, 20+ years, but appears to work. A cheaper entrypoint for sure, he is willilng to borrow it "for now" and mentioned.
https://www.keysight.com/us/en/product/E3631A/80w-triple-output-power-supply-6v-5a--25v-1a.html

9

Test Equipment / Re: Measure capacitor for ESL and ESR and C over frequency

« Last post by tggzzz on Today at 11:29:06 am »

Thanks, the El Cap that we need ESL and ESR for, at 450khz, is...

EDH477M050S9SAA
https://www.mouser.co.uk/datasheet/2/447/KEM_A4049_EDH-3316662.pdf

Also, need ESL and ESR  for a 10uF, 50V, 1210, X7R   MLCC

Bully for you.

RTFM.

If the FM doesn't tell you, choose another capacitor.

10

Microcontrollers / Re: It Came from Mainland China: Bootleg MCS-251 "32-Bit 8051"

« Last post by Dass347 on Today at 11:28:28 am »

AFAIK, the STC32 parts currently have only single tool chain support - needing Keil C251 to code.

Yup, and Keil is terrible, too. The assembler and linker needed a bunch of weird prodding to actually produce .hex files mapped onto the expanded MCS-251 address space, otherwise anything outside of the traditional 64K of 8051 address space is thrown out without any warning or error. I imagine that Keil C251 was just developed out of Keil C51, hence the weird behavior.

Also, Keil C251 requires a roughly ~$3,000 license to make programs larger than 2 kilobytes. After some Baidu searches, it looked like what happened was that an illegal key generator was released in 2020, essentially unlocking the software, and then the development of the MCS-251 clones started.

Yes, the STC8H parts have moved the '1T' 8051 space.

The interesting thing about this is that although the STC32G parts are faster overall due to being 32-bits, some traditional 8051 instructions take longer on the STC32G than the 8-bit STC8H parts.

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