Pinned post

Current projects:

  • DIN rail domotic devices (Active)
  • DMX Panel Controller (Closing - Pending)
  • ExamPCB LED (Paused)
  • PCBID/PCBIDB (Background)
Pinned post

Hello cathode people, time!

This is my technology-oriented account. Just one side of me.
I work as a hardware engineer and teacher living in Madrid. I'm committed to the free culture philosophy, supporting FLOSS and FreeHardware. In my spare time I develop things and collaborate with people. I like geek stuff. Also a game developer wannabe.

Riley ⚧ boosted

The person in charge of the Nostromo set for Alien (1979) invented this interstellar standard for signs and labels in spaceflight

Riley ⚧ boosted

Discourse is the ultimate RAM eater, rather than a forum.

Riley ⚧ boosted

"Desktop apps suck. Instead I want to have to build and maintain two completely separate codebases and then write APIs between them. The frontend should only be able to be run inside a container that Google wrote." - Web developers

Riley ⚧ boosted
Riley ⚧ boosted
This is a pretty cool project
https://github.com/Y2Z/monolith

> A data hoarder’s dream come true: bundle any web page into a single HTML file. You can finally replace that gazillion of open tabs with a gazillion of .html files stored somewhere on your precious little drive.
Riley ⚧ boosted

What's your primary OS?

Boosts appreciated for sample size :)

People familiar with Node-RED and MQTT, I have a quick question:
MQTT In nodes generate the _topic property only if they are connected to a local broker.
What is the intention of msg._topic and how does it differ from msg.topic?
I have not found any documentation on the subject.

Solved. In case anyone encounters this problem, the culprit is called Pass-by-reference.

Show thread

I'm seeing about variables in Node-RED, and that reading them creates a private copy and makes me think about the possibility of collisions and data corruption when writing data that has already been written but is not in your private copy. Is Node-RED maintained on a wishful thinking basis or am I missing something?

Anyone explain to me how to avoid that? Thanks

New no update: The only contact I have at PCB factories who has responded to my request to try to find this component, finally tells me that he can't do anything. They don't want to share their list of distributors or suppliers that could potentially have this autotransformer and want this paperwork to go through them (i.e., ask them for PCBA and then they look for it).

This then seems like a dead end. If I cannot dispose of this autotransformer, what other options do I have left?
Any comments would be appreciated.

I'm pretty discouraged seeing that the whole project may drop because I can't find something that makes a piezo sound.

Show thread

The real consequences of this stock crisis will be seen in the coming years, through ingenious solutions of how the lack of stock has been overcome and who has benefited from it.

Show thread

With the estimated production timelines of stm32, I guess they won't be looking to train new developers in the next few years.
There is going to be a knowledge gap in electronics engineers.

Riley ⚧ boosted

Today I have been playing again with the piezo driver circuit.

In my previous attempts, I was unable to find anything that fits the bill. The sound circuit has to generate a loud alarm signal, and it has been a problem from the beginning.

From the simplest circuit with a transistor, to push-pull, differential, resonant circuit... None of them achieved the output level I needed.

So today I took the next step: auto/transformers. The first thing I found is that I have to change the power supply approach. Of the different options I've tried, two have worked well. Now I have a dilemma and need your help:

I can mount an autotransformer that works very well but with unknown manufacturer and MPN (aliexpress supplier) OR mount a transformer with known manufacturer and MPN, that doesn't work so well, electrically is not the right one (wrong impedances) and is ten times more expensive.

New update: Actually it is without update. No one of the people consulted has told me anything. Only one of the factories has told me that they can look for the component if I send them the gerbers. In order to develop the gerbers I need to know the component! So I have no update, no autotransformer.

Show thread

Update:

I have found a chinese manufacturer of inductors and transformers that makes them to order, which is still not what I am looking for but may be a starting point to keep looking?

I have asked aliexpress sellers who sell the autotransformer, about which manufacturer provides them. I am not expecting answers.

And I intend to ask my contacts at PCB fabs if they know manufacturers or suppliers of these autotransformers.

Anyone else I can contact to try to find this component?

Show thread

I would really want to be able to choose the autotransformer, if I could put an MPN on it, instead of a transformer which is not appropriate. Does anyone know where I can keep looking? Anything I may have missed? What would you do in this situation?

If you don't know what I'm talking about, do a search with "alarm boost inductor" or "three pin inductor". They are small autotransformers for driving piezos. They have the right impedance to be driven from low voltage and move a piezo at the other end.

The transformer option with known manufacturer, are audio transformers for loudspeakers, that although there are in the amplification ratio I need with a small footprint (larger than the autotransformer), the impedances do not match, having among other things an excessive power consumption.

It's amazing how simple the idea of a circuit that makes a piezo sound is, and how much effort and money it's taking.

Show thread

This is for an open-source device, which although I don't know if it will be PCBA manufactured or hand-assembled, it is imperative that it has a BoM covering all the components that will ensure that you can get all of them.

As an alternative solution, I went so far as to consider providing the necessary instructions to be able to hand fabricate this transformer. I even got my hands on a henriometer which I already showed. But it doesn't seem sustainable to me that the end user has to get with the spool, core and magnetic wire for this. More so if the device were to be mass produced. This is out of the question.

I have not been able to find distributor or manufacturer that has these autotransformers, with manufacturer and part number. And I have searched extensively. I am at a loss for ideas on how to get a manufacturer that has this component associated with a part number, and with stock that is available by the unit. Hence my dilemma.

Show thread

Today I have been playing again with the piezo driver circuit.

In my previous attempts, I was unable to find anything that fits the bill. The sound circuit has to generate a loud alarm signal, and it has been a problem from the beginning.

From the simplest circuit with a transistor, to push-pull, differential, resonant circuit... None of them achieved the output level I needed.

So today I took the next step: auto/transformers. The first thing I found is that I have to change the power supply approach. Of the different options I've tried, two have worked well. Now I have a dilemma and need your help:

I can mount an autotransformer that works very well but with unknown manufacturer and MPN (aliexpress supplier) OR mount a transformer with known manufacturer and MPN, that doesn't work so well, electrically is not the right one (wrong impedances) and is ten times more expensive.

Today I have finally been able to resume the icodome project, after a break of a few weeks due to too much work. I have been able to continue prototyping and validating parts! Next is the piezo driver circuit.

Show older
Cathode Church

A place for trans makers, coders, tinkerers and dreamers.