Recently on this thread I talked about designing my electronic load. I want a "not burning hot" dissipation, and assemble little modules ( scaling and offsetting the dac output from a microcontroller to command the gate of the mosfets ; scaling and offsetting the voltage output of a current sensor to feed an adc to that same micro-controller ; the connector circuit to the device under test, with a 3A fuse and the current sensor) because I want to distribute the cost of pcb over time, and eventually reuse modules to have, for instance, 2 independent current sinks, one for a 5V rail, another for a 12V rail *wink*
I have studied the load explained on eevblog #102...
...and another one by Great Scott...
...and then I learn about so called "logic level" mosfets and "rail-to-rail"/"full swing" op-amps, and relearned about op-amps generally.
Today I received the first prototype pcb of the so called "Voltage Controlled Current Sink", a grandiose name for a pair of mosfets attached to their heatsink, and a pair of connectors positioned in symmetry to allow more freedom to assemble with the other part (still in the drafting notebook).
I will revise it a little, as I finally do not like so much having one single connector for each 3A lines, so I will divide into 3 connector each. And now that I see it, my copper plane for the sources of the fets looks a little bit silly near the mosfet. The mounting holes are also a bit to close from the edge.
Sporniket's log on hardware stuff
Re: Sporniket's log on hardware stuff
Be interesting to see how it goes
I'm using a 300watt 22R rheostat for my testing so far
I'm using a 300watt 22R rheostat for my testing so far
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Re: Sporniket's log on hardware stuff
Yes, I remember having read that one of your testing got your rheostat glowing red.
Thanks for the interest, gives me one more reason to finish
Re: Sporniket's log on hardware stuff
This last week-end before payday, I reworked the pcb of my current sink ; as I told, I divided the high-current ports into 3 connector each, and the DUT- entry is re-labeled 'GND', that I have forgotten in my head, comparing to the schematic on eevblog. Before connecting to DUT+, one will have to add the current sensor (I will use one of those https://fr.aliexpress.com/item/1005001698417485.html, the 20A version) and a fuse.
I also work on the circuit that convert a DAC output (e.g. 0V to 3.3V) into a small range ( 0 <= Vmin to Vmax <= VCC ) to the mosfet gate, and then the circuit that convert the voltage of the current sensor ( from VCC/2 to VCC/2 + 0.1V per amp) into the range 0V to Vmax<= VCC for an ADC input. I thought to have 1 board for each circuit, but components are so tiny that it fit in the planned 5cm×5cm board.
Here are the schematics, for those that are interested...
I also work on the circuit that convert a DAC output (e.g. 0V to 3.3V) into a small range ( 0 <= Vmin to Vmax <= VCC ) to the mosfet gate, and then the circuit that convert the voltage of the current sensor ( from VCC/2 to VCC/2 + 0.1V per amp) into the range 0V to Vmax<= VCC for an ADC input. I thought to have 1 board for each circuit, but components are so tiny that it fit in the planned 5cm×5cm board.
Here are the schematics, for those that are interested...
Re: Sporniket's log on hardware stuff
I ordered and got my components, here is the BOM, with the price at the time of writing :
Code: Select all
SEL - CURRENT SINK
SKU Mouser SKU Manufacturer Manufacturer Qty. U. Price (EUR) T. Price (EUR) Description
588-FA-T220-64E FA-T220-64E Ohmite 2 2,39 € 4,78 € HEATSINK FOR TO-220 BLK ANODIZED
726-IPP80N03S4L03AKS IPP80N03S4L03AKSA1 Infineon 2 1,82 € 3,64 € MOSFET N-Ch 30V 80A TO220-3 OptiMOS-T2
Code: Select all
SEL - BRIDGE CONTROLLER TO MODULES
SKU Mouser SKU Manufacturer Manufacturer Qty. U. Price (EUR) T. Price (EUR) Description
755-LMR932FVJ-GE2 LMR932FVJ-GE2 ROHM Semiconductor 3 0,508 € 1,52 € Op amps - Low Power Input-Output Full Swing Operational Amplifier
594-ACASA1000S1002AT ACASA1000S1002P1AT Vishay 3 0,906 € 2,72 € Resistor networks-Resistors packs 100 / 10K ohms AEC-Q200
652-3296Y-1-503LF 3296Y-1-503LF Bourns 4 1,84 € 7,36 € Trimpot - THT 3/8" 50Kohms Sealed Vertical Adjust
581-12063C104JAT2A 12063C104JAT2A Kyocera AVX 3 0,296 € 0,89 € MLCC - CMS 25V 0.1uF X7R 1206 5%
Re: Sporniket's log on hardware stuff
One of my goal is to power my H5 with this type of USB-C PD module :
Of course I will need a proper USB-PD wall plug (up to around 60W to be extravagant, but 30W would be enough) and a proper cable. And I don't plan to power the 12V rail.
At first I want to use the basic 5V@3A, hopefully as is. Then, as I add some upgrade, I may have to use higher voltage (9V or 12V), thus needing a converter circuit. The overall goal is to have a very small footprint, to get rid of the metal plate, replaced by a 3D printable armature for support, or just some nylon spacers, to free most of the space over the area usually covered by the legacy psu.
Of course I will need a proper USB-PD wall plug (up to around 60W to be extravagant, but 30W would be enough) and a proper cable. And I don't plan to power the 12V rail.
At first I want to use the basic 5V@3A, hopefully as is. Then, as I add some upgrade, I may have to use higher voltage (9V or 12V), thus needing a converter circuit. The overall goal is to have a very small footprint, to get rid of the metal plate, replaced by a 3D printable armature for support, or just some nylon spacers, to free most of the space over the area usually covered by the legacy psu.
Re: Sporniket's log on hardware stuff
With my latest sessions of work, like here, I've grown fed up with my current soldering iron (a basic one, 25W, no temperature setting). I planned to wait 6 monthes-1 year before having one of those TS100 or alike, because I prioritize a good enough scope for this Xmas.
But today I found one of those cheap things on A--Express for 10€ (50% off) : 80W, temperature setting, and a set hakko-900 style tips... That will do for the time being. The drawback to me is no earthing.
But today I found one of those cheap things on A--Express for 10€ (50% off) : 80W, temperature setting, and a set hakko-900 style tips... That will do for the time being. The drawback to me is no earthing.
Re: Sporniket's log on hardware stuff
I always disconnect the earth on my soldering iron because it causes more damage otherwise.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Re: Sporniket's log on hardware stuff
Ha, so finally it will be an advantage instead of a drawback (anyway I didn't planned to touch the tip when it's live )
edit : reformulation.
- olivier.jan
- Posts: 213
- Joined: Mon Jun 01, 2020 8:00 am
Re: Sporniket's log on hardware stuff
If you haven’t ordered yet, I would really recommend getting a Pinecil instead : similar to TS100, but can use USB-C and only 24USD. I’ve been using it for a few months, and it’s really awesome for the price.
And if you are in «Region Parisienne » and want to test, feel free to PM me.
https://pine64.com/product/pinecil-smar ... ring-iron/
And if you are in «Region Parisienne » and want to test, feel free to PM me.
https://pine64.com/product/pinecil-smar ... ring-iron/
Retro stuff
520 STF/ 1040 STE / Mega ST / 2 Mega STE / 2 H5
2 x 600XL with U1MB /SOFIA 2/ AVG CART / and a few 1050
Apple //c, Commodore 128, Mac Classic, SE/30, LC, IIvi and PB G3 (Clamshell)
Amiga 600 and a few 486 and 386.
Many Nintendo G&W and other electronic games from the late 70s/early 80s.
520 STF/ 1040 STE / Mega ST / 2 Mega STE / 2 H5
2 x 600XL with U1MB /SOFIA 2/ AVG CART / and a few 1050
Apple //c, Commodore 128, Mac Classic, SE/30, LC, IIvi and PB G3 (Clamshell)
Amiga 600 and a few 486 and 386.
Many Nintendo G&W and other electronic games from the late 70s/early 80s.