Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt

[BlownCorona]

i completely forgot to get those preamp bits out for @Metalhead96 will do that asap. 

OG opamp was an which is NLA though can be had from ebay, there are probably suitable cheap alternatives 

additional bits required would be the 100k log pot for bass, 1M reverse log pot for treble and 25k log pot for volume. I went to great lengths to get these pots with center detents just like original which are NLA and required me to buy about 9 pots and disassemble and built up with various parts. however im pretty sure you can buy the required values if you arnt fussy.

https://www.digikey.co.nz/en/products/detail/texas-instruments/LM4250CN/3695231

[h4nd]

https://octopart.com/search?q=LM4250CN&currency=NZD&specs=0

I have a credit at win-source, but it won't cover the shipping

I also have a moderate collection of old pots in high-ish values like these, from the bad olde tube-amp days

 

[BlownCorona]

is that an smd variant or just a stock image? 

[h4nd]

Data sheet says DIP, so must just be a stock image

CH metal can would be sweeeeet. You could probably even stuff them in the DIP socket, if you had the nice ones with the round machined receptacles.

[h4nd]

6 hours ago, h4nd said:

I also have a moderate collection of old pots in high-ish values like these, from the bad olde tube-amp days

Oops, no I don't: hoarder fail. After ~1/4 century, I tossed the worst. About 2 months ago.

Ecotec services in 139A Wordsworth St might be worth an email / look

[BlownCorona]

11 hours ago, h4nd said:

Oops, no I don't: hoarder fail. After ~1/4 century, I tossed the worst. About 2 months ago.

Ecotec services in 139A Wordsworth St might be worth an email / look

they can be had for low cost, just missing the centre detents. its only because i was chasing authenticity on that front that i went to great lengths. any normal person would simply fit a knob with a marker and a corresponding centre position on the base. 

[h4nd]

On 13/08/2025 at 11:01, h4nd said:

Doing a DigiKey order in a day or 3.

Any of you (Chch or nearby) nerds need particular shit not avail on AliEx, wanna bypass the shipping fee?

@EpochNZ @Metalhead96 @BlownCorona?  

Tag any nerds I've missed.

 

edit: Shit I love DigiKey - select the part parameters:

• Sorts by cheapest first

Check the part, yeah, it's good. Go to order 5x

• That'll be NZ$2.95,   but if you click here for this alt number for the same part, you can get 10x for $2.50

It's like they want you to come back, or something. 

Weird.

Last orders, gentlemen please.

Settling tonight.

[h4nd]

On 13/08/2025 at 20:48, h4nd said:

CH metal can would be sweeeeet. You could probably even stuff them in the DIP socket, if you had the nice ones with the round machined receptacles.

@BlownCorona @Metalhead96 https://www.worldwayelec.com/pro/national-semiconductor/lm4250ch

[HighLUX]

Where can I source that acrylic welding glue the good stuff thats full of carcinogens 

[Stu]

Weldon16 or Acryfix. PSP and Mulford Plastics sell it. We use gallons of the stuff.

[440bbm]

Cable ties. Lots of them haha 

[h4nd]

Custom PCBs are astonishingly cheap these days, 15x15mm, 10x28, 86x129mm:

(JLC PCB, but only because they have a plug-in for KiCAD to prep the gerber etc files for them)

[Bling]

I think I watched a Strange Parts video on the making of those, pretty sweet. Just imagine the cost of making them here.

[rusty360]

So I following the old school way and currently have juniors chromebook in quire a few pieces, I'm pretty sure the lcd backlight fuse has died. It's a tiny little farker on the board.

Any ideas were I could get one from in nz?

[rusty360]

Just now, rusty360 said:

So I following the old school way and currently have juniors chromebook in quire a few pieces, I'm pretty sure the lcd backlight fuse has died. It's a tiny little farker on the board.

Any ideas were I could get one from in nz?

 

[rusty360]

So I bridged it with a bit of wire and solder and it's all go! Will it now blow up and burn down the house? Or don't worry about push on!

[NickJ]

 

A possible fix inline with an engineering safety discussion had with @h4nd, may/maynot be the viable option

You'll probably need to squish it a bit with a hammer to fit

[igor]

Audible blow fuses?

[h4nd]

Yeah look, if a properly qualified person selects an appropriate fuse from a guide based on the application, bearing in mind any special considerations: You're probably golden 'ill it hits court.

Guide:

...

..

.

Pick any number from the outside of the machine and match to below:

[h4nd]

Anyhoo

New computer has arrived