Sporniket's log on hardware stuff

[sporniket]

Reaching the completion of placing the components on the PCB, and I found some changes to apply to the 32Mhz clock and modulator clock circuit :

• a C67 that does not appears on the schematic (neither in the same circuitry on the STF and STe), and I forgot R140. My guess is that it was present in the initial circuit but quickly deemed unnecessary. But that it was not removed from the PCB.
• a forgotten R140 between U41 and the base of Q11

2023-08-15--errata-32mhz-clock.png (313.18 KiB) Viewed 366 times

[sporniket]

Recently I got inspired about how I want to implement the powering of my STE using a USB phone charger (see experiment there : viewtopic.php?f=9&t=5939)

Instead of doing 3dmodeling of 3d printed parts, I decided to reuse the original mount bracket, and replace the psu board. Then I would hack an IEC 60320 C13 plug to feed a DC5V through it. Thus, no casing, plug or power switch mistreated

dc5v-for-atari-stf.png (329.15 KiB) Viewed 338 times

Capture d’écran du 2023-08-25 15-30-57.png (90.96 KiB) Viewed 338 times

I'll have to check what I could order at mouser to get the free shipping, so not before end of september for the next step...

[exxos]

Oddly I managed to power my H5 from the USB port from my PC

[sporniket]

Oddly I managed to power my H5 from the USB port from my PC

That makes it a quite huge power supply

[sporniket]

A little micro-step forward for my project of DC power supply for my STe : I hacked a IEC 60320 C13 and put a 55-21 barrel jack connector, so that I can either use a usual power brick (I found one on amazon, 5V at 4Amps, that I have to test), either a USB power delivery trigger with a suitable jack connector. I used the plastic flexible sleeve, that fit the barrel jack connector, to position it correctly.

2023-09-24--01-modified-plug-innards.jpg (65.27 KiB) Viewed 258 times

2023-09-24--02-modified-plug-barrel-jack-side.jpg (50.51 KiB) Viewed 258 times

2023-09-24--03-modified-plug-socket-side.jpg (58.03 KiB) Viewed 258 times

[exxos]

Nice

[ijor]

A little micro-step forward for my project of DC power supply for my STe : I hacked a IEC 60320 C13 and put a 55-21 barrel jack connector, so that I can either use a usual power brick (I found one on amazon, 5V at 4Amps, that I have to test), either a USB power delivery trigger with a suitable jack connector. I used the plastic flexible sleeve, that fit the barrel jack connector, to position it correctly.

Wow. Very cool. I guess you are not selling this, otherwise I want at least a couple!

[sporniket]

Thanks for your kind words.

@ijor I plan to get parts, assemble a few units and perform some trials during next month. I take note of your interest.

[sporniket]

This evening, I was feeling like setting up my scope, my electronic load, and test my 5V/4A/20W power brick to check that it will be good enough to power my STe :

2023-09-29-00-setup.jpg (200.45 KiB) Viewed 185 times

• I got the electronic load here : https://fr.aliexpress.com/item/4001153199791.html
• the power brick is from there : www.amazon.fr/dp/B01HRR9GY4

2023-09-29-01-electronic-load-in-action.jpg (106.44 KiB) Viewed 185 times

I started with measuring the voltage when the load requires 2A of current. The voltage is in the 5-5.2V range, the ripples are small, and there is no spike :

2023-09-29-02-scope-2A-DC.png (34.99 KiB) Viewed 185 times

2023-09-29-03-scope-2A-AC.png (36.59 KiB) Viewed 185 times

Then I setup the load at 3.9Amp to see how it goes near the limit of the power brick. The voltage drops a little bit under 5V (around 4.8V).

2023-09-29-04-scope-3.9A-DC.png (35.19 KiB) Viewed 185 times

2023-09-29-05-scope-3.9A-AC.png (35.5 KiB) Viewed 185 times

Then I setup the load at 3.8Amp, with the intent to let it work for an hour.

2023-09-29-06-scope-3.8A-DC.png (34.61 KiB) Viewed 185 times

The voltage is a little bit more close to 5V, but the average is quite the same as at 3.9A. It's better at 3.7/3.6A and below.

Also, after one hour powering the load at 3.8A, the temperature of the brick is warm (I have a K-probe thingy, it is in the 45-50 degrees)

Thus I conclude that this power brick will be safe enough for my experiment to come.

[exxos]

Do electronic loads cause "noise" on the rails it's powering ? I've never used a electronic load. So don't know how it compares to a resistor load.