NEW MSTE/TT & ST PSU ? (well not really)

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NEW MSTE/TT & ST PSU ? (well not really)

Post by exxos » Thu Apr 12, 2018 2:41 pm

As many know I created alternative power supplies for the STF/E/Falcon. About once a week I get asked if I will design a new MSTE PSU. Basically the answer is no.

I sometimes get asked about ST PSU's, I will recap about this also below..


In terms of the transformer, the MSTE one needs easily twice the size of the transformer I am already using. By the time one is fitted inside the case, there is practically no room left for any electronics. I did design the 5V & 12V switch mode circuit and even started the PCB a couple of years ago, but even that is starting to get physically too large even without the transformer. My design has moved on since with my current power supplies which can deliver more amps small footprint. So it may be possible to create a small enough PCB, but the problem remains of physically fitting the transformer inside the case.

Not only that we have the -5 & -12v rails which would also need additional circuitry and may even need another tap on the transformer. I could go down the route of having some custom transformers made which will maybe physically fit, but this could mean £100+ per these transformer and a low-volume run. So it is not really realistic by any means to have a transformer-based power supply for the MSTE & TT machines.

The only way it would fit would be to create a switch mode design very similar to the existing one. But then it would still need a transformer which would probably have to be custom-made anyway. Either that or reuse the existing transformer. In which case I think it is just pointless as it would be easier just to update and service the existing one rather than create a very similar design.


I was contemplating a couple of years ago in creating a ST power supply. Basically slightly shrunk down version of the current STF PSU which I am using currently. I even purchased a metal case for the PCB to slot into and even bulk purchase lots of connectors for this.

The problem is, all the wiring and drilling in the case would take a lot of time. So much time in fact I even projected the cost for this power supply would be easily £150-£200. I did ask the community at the time what their thoughts were about this. Basically they think the price is too high, and I even agree with people in this respect. But drilling holes in cases is time-consuming, similarly screwing them onto the case, and then doing all the wiring the PCB is also time-consuming. The costs of the case is actually a fair bit as well. It is a heatsink case as obviously the regulators at the time would need heatsink to cool them.

I was even thinking this power supply would be powerful enough to power the two floppy drives as well as a auxiliary output for a hard drive such as Ultra Satan. So rather than needing four separate power supplies, everything would plug into one box. I think the idea is a good one and the overall product would be really good. But unfortunately he just cannot produced at a realistic price. More so as I simply do not have time to do wiring and drilling so it would have to be done elsewhere which would of course increase the costs.

So yes I can produce the PCB which will physically fit the case I chose already. If someone else wanted to invest the time to the wiring and drilling of the cases, and I can look into having the PCBs manufactured and even assembled. As the me personally, I just do not have the time and cannot produce this at a realistic price. There may be other places elsewhere in the world which can do case fabrication and assembly cheaper than I can have it done here. But of course someone would have to invest a lot of capital starting this production up.
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Re: NEW MSTE/TT & ST PSU ? (well not really)

Post by troed » Thu Apr 12, 2018 5:00 pm

I must confess, since the ST already has an external power brick I think a picoPSU is the best choice there. I desoldered the exising power connector, put a picoPSU internally and it supplies the 5/12/-12 in ample amounts to also be used for other internal mods like an HxC slim etc ...

Of course, that's not a simple plug'n'play mod. It would be possible to make that off a pico and an ST power connector though.

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