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Advice for regulated multi-voltage power supply?

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#1 jeffsuth

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Posted 26 July 2021 - 02:12 PM

I recently bought an imaging camera that I am unable to find the correct proprietary power supply for, so I'm wondering how I would go about building one (starting as a mental exercise, we can go from there...). It looks to be fairly complicated, and there's a good chance that even if I get the PSU perfect, it will still not work - so cheaper would be better.

 

These are the requirements of the different required voltages:

+3.6 V @ 1 A

+17 V @ 0.5 A

+37 V @ 0.2 A

-15 V @ 0.3 A

6-15 V @ 3.8 A

 

Offhand, I was thinking a couple possibilities:

1. Find individual components with the proper amperage and hook all of their negative terminals to a common ground, and for the -15V, hook the positive to the ground. Not sure if this works though...

 

2. Get a 60V DC PSU, and use resistors somehow to pull off the required voltages, using 0 as the -15 and using the 15V as ground for the camera. Not sure how to handle the amperage requirements.

 

Does anyone here have any better ideas? Is there a multi-channel programmable PSU that I could just cover all bases with here? I'm a software person, not so much a hardware person, so if I could just do this via software somehow, that would be amazing!



#2 steveastrouk

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Posted 26 July 2021 - 02:26 PM

Are you sure about all these rails ? What's the camera ?

 

Option 1 would work, but lets check exactly what's needed.

 

Option 2 is absolutely NO. VERY bad idea. No. Don't go there.


Edited by steveastrouk, 26 July 2021 - 02:27 PM.

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#3 bbasiaga

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Posted 26 July 2021 - 03:15 PM

Can you post what kind of camera it is, along with some pictures of it and the power connector? 

 

It would seem very unique to me for it to have that many power inputs.  The couple that I have owned and the few that I have seen all have a single input for the power.  I suppose any internal voltage changes are handled within.  

 

-Brian


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#4 fftulip

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Posted 26 July 2021 - 03:18 PM

As stated above, don't use resistors to drop the voltages, because that would be an unregulated supply (probably bad for the camera).

For the supplies 1A or less you can use 3 terminal regulators as most of them can handle at least an amp (but be careful, they may need heat sinks to dissipate the power).  Usually the voltage is set with resistors or a pot (variable resistor) if it is not a fixed voltage regulator.  They make specific 3 terminal regulators for negative voltages.  I would get help from an EE or someone who's used regulator IC's before if you have no experience.  It' pretty easy to blow up parts, cause shorts, or worse, destroy the camera if you don't know what you're doing.

For the 6-15V you can probably get an inexpensive 12 or 13.8V separate power supply to handle that (most regulators IC's won't be able to supply 3.8A).


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#5 grubba

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Posted 26 July 2021 - 03:59 PM

If you are going the DIY route, use buck converters off a common power source. The issue is the 37V. That's unusually high and would likely require its own supply as most (cheap) DC/DC converters don't go that high. For all the other voltages, you could use a single 24V power source and these:

 

https://www.amazon.c...nics,149&sr=1-1

 

What camera is this? "37V" is a rather unusual value.


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#6 grubba

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Posted 26 July 2021 - 04:04 PM

This one will take the 24V input and boost to 37V though it's quite an overkill at 8A (it would work just fine though). 

 

https://www.amazon.c...tronics&sr=1-18

 

The idea is that you can find these converters and build your own multiple outputs off one single source. They tend to be cheap but you will need to do all the soldering and voltage calibration yourself.


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#7 don clement

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Posted 26 July 2021 - 05:43 PM

Switching PS is inherently noisy so be sure it's filtered well for use in a camera. 

 

Don 


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#8 Jon Isaacs

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Posted 26 July 2021 - 05:59 PM

Can you post what kind of camera it is, along with some pictures of it and the power connector? 

 

It would seem very unique to me for it to have that many power inputs.  The couple that I have owned and the few that I have seen all have a single input for the power.  I suppose any internal voltage changes are handled within.  

 

-Brian

 

:waytogo:

 

It seems like this would have to be a used camera that is essentially missing the power supply.  It's hard to imagine a camera that needed so many different voltages would not have a dedicated power supply.

 

The make and model of the camera would be good to know.

 

Jon



#9 jeffsuth

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Posted 26 July 2021 - 07:40 PM

Thanks for the thoughts and ideas folks - I'll try to address all comments later, but for now, seems the recurring theme is which camera. It's a Photometrics Evolve 512 EMCCD I bought used on Ebay. The power cable pinout is very ugly, and there is a data connection involved with the power supply, so these voltages are only the tip of the iceberg unfortunately!



#10 steveastrouk

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Posted 26 July 2021 - 08:28 PM

If its still a production camera, I'd seriously look at biting the bullet and buying theirs. Seriously, there is a LOT of work here. The sequencing of the supplies is likely critical, overshoot and under shoot as supplies sequence might destroy the camera.


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#11 astrohamp

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Posted 26 July 2021 - 08:37 PM

Think carefully if all the effort is worth it, especially for field use.

My Photometrics was not worth the DIY effort, especially since cooling involved a supply of liquid nitrogen.  Fantastic research tool, poor field implementation. 

Good luck!


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#12 grubba

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Posted 26 July 2021 - 10:32 PM

Thanks for the thoughts and ideas folks - I'll try to address all comments later, but for now, seems the recurring theme is which camera. It's a Photometrics Evolve 512 EMCCD I bought used on Ebay. The power cable pinout is very ugly, and there is a data connection involved with the power supply, so these voltages are only the tip of the iceberg unfortunately!

Yup, found the manual here: https://www.photomet...e5120Manual.pdf

 

That connector is a DB25, which is rather common. However, if you don't have the cable, wiring it will be a pain. The manual says 2009 but it looks like something from the 1990s. I'm not sure it's worth the effort. I doubt you would find software/drivers for anything newer than Windows XP. Even if you do manage to power it and get a proper cable, it seems it needs its own software and the link to the computer is FireWire? It requires an external liquid chiller for -100°C cooling? Are you planning on installing it on a telescope? For 512x512 resolution?


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#13 BGRE

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Posted 27 July 2021 - 01:32 AM

CCD image sensors with electron multiplying output stages were introduced in 2001. The very low readout noise floor (quantum counting statistical noise is still present) achived with an emccd can be useful when imaging faint objects.
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#14 mdavister

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Posted 28 July 2021 - 12:18 PM

I read through the manual, looks like an interesting find. As for the power supply, there are DC-DC bricks that you can tie together to generate the voltages. The +37 will be the harder one, not a standard voltage. Probably be easiest to use a dual output 18V (if you can find one), although you may have to homebrew a regulator for the 37V. If you need some help let me know, I've dabbled with power electronics for some time now (day job).


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#15 jeffsuth

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Posted 28 July 2021 - 01:46 PM

Option 2 is absolutely NO. VERY bad idea. No. Don't go there.

This is great to hear - rules that out right away!

 

As stated above, don't use resistors to drop the voltages, because that would be an unregulated supply (probably bad for the camera).

For the supplies 1A or less you can use 3 terminal regulators as most of them can handle at least an amp (but be careful, they may need heat sinks to dissipate the power).  Usually the voltage is set with resistors or a pot (variable resistor) if it is not a fixed voltage regulator.  They make specific 3 terminal regulators for negative voltages.  I would get help from an EE or someone who's used regulator IC's before if you have no experience.  It' pretty easy to blow up parts, cause shorts, or worse, destroy the camera if you don't know what you're doing.

For the 6-15V you can probably get an inexpensive 12 or 13.8V separate power supply to handle that (most regulators IC's won't be able to supply 3.8A).

Thanks for the suggestions on 3 term regulators - I'll check that out...

 

If you are going the DIY route, use buck converters off a common power source.

...

The idea is that you can find these converters and build your own multiple outputs off one single source. They tend to be cheap but you will need to do all the soldering and voltage calibration yourself.

I appreciate these suggestions and your amazon link examples, thanks!

 

If its still a production camera, I'd seriously look at biting the bullet and buying theirs. Seriously, there is a LOT of work here. The sequencing of the supplies is likely critical, overshoot and under shoot as supplies sequence might destroy the camera.

Truer words are never spoken smile.gif. Unfortunately, despite my best attempts, as a mere individual (not corporation or research institute), I am unable to get any support from them for this camera - no parts or even information! I have tried to get approval, but no luck. Still checking ebay every day, but have yet to see anything but cameras and sometimes cameras with PSU's. If anyone has an extra Evolve 512 PSU kicking around, PLEASE let me know!

 

Think carefully if all the effort is worth it, especially for field use.

My Photometrics was not worth the DIY effort, especially since cooling involved a supply of liquid nitrogen.  Fantastic research tool, poor field implementation. 

Good luck!

Hah, yeah, I hear you. The old ones are much more challenging to work with I think. At least the interface on this one is firewire, so at least somewhat consumable! If it weren't for the darn power supply it would be too easy!

 

Yup, found the manual here: https://www.photomet...e5120Manual.pdf

 

That connector is a DB25, which is rather common. However, if you don't have the cable, wiring it will be a pain. The manual says 2009 but it looks like something from the 1990s. I'm not sure it's worth the effort. I doubt you would find software/drivers for anything newer than Windows XP. Even if you do manage to power it and get a proper cable, it seems it needs its own software and the link to the computer is FireWire? It requires an external liquid chiller for -100°C cooling? Are you planning on installing it on a telescope? For 512x512 resolution?

It's nice the include the pinout in the manual though, eh? You can get soldered DB25 adapters so I don't think the wiring will be the hard part for me. They do have drivers and an SDK, so I should be able to get it working on something newer, but worst case, I just set up an XP box for a different Photometrics camera, so I can piggyback off that. Also, my model doesn't require an external chiller as it is air cooled to -85C. As for the 512x512 comment, I hear what you're saying, but the call of lucky imaging for DSO's is real wink.gif. 90+%QE across visible + almost no read noise (or dark noise at that temp) is nothing to scoff at. May not be going for wide-field here, but sure would be fun for galaxies/pn's.

 

CCD image sensors with electron multiplying output stages were introduced in 2001. The very low readout noise floor (quantum counting statistical noise is still present) achived with an emccd can be useful when imaging faint objects.

+1 to this!

 

I read through the manual, looks like an interesting find. As for the power supply, there are DC-DC bricks that you can tie together to generate the voltages. The +37 will be the harder one, not a standard voltage. Probably be easiest to use a dual output 18V (if you can find one), although you may have to homebrew a regulator for the 37V. If you need some help let me know, I've dabbled with power electronics for some time now (day job).

Does this really work? I figured if there was a DC-DC power supply, if I tried to daisy chain the + of one to the - of the other to add the voltage like you would with batteries, it would just short... How can I tell if it short or not? It seems like it would just be like adding 2 sets of wires to each terminal of a battery and hooking the + to the -...

 

Anyway, from what you folks are saying, it seems like it's a reasonable thing to just get a bunch of smaller regulated power converters and draw all from the same 12V source for each required rail... Thanks all!


Edited by jeffsuth, 28 July 2021 - 01:46 PM.


#16 pejorde

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Posted 28 July 2021 - 02:22 PM

Years ago I built a power supply for my "Cookbook" CCD camera that required an assortment of different voltages: -15VDC and +15VDC filtered for the camera electronics, 5 amp adjustable 0-6VDC current for the Peltier element, and 12VDC for the cooling pump/fan. The unit (described in the CCD Camera Cookbook) is quite simple and based on AC transformers, bridge rectifiers and filtered by electrolytic capacitors, and a power transistor (2N3005) and voltage regulator (LM317T) for the regulated current:

 

DSC00785.JPG

 

I should assume something similar could be set up to match your requirements.

 

Per Erik

 


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#17 bbasiaga

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Posted 28 July 2021 - 03:01 PM

 

 

Does this really work? I figured if there was a DC-DC power supply, if I tried to daisy chain the + of one to the - of the other to add the voltage like you would with batteries, it would just short... How can I tell if it short or not? It seems like it would just be like adding 2 sets of wires to each terminal of a battery and hooking the + to the -...

 

Anyway, from what you folks are saying, it seems like it's a reasonable thing to just get a bunch of smaller regulated power converters and draw all from the same 12V source for each required rail... Thanks all!

Nope...no shorting.  + to - on the same battery will short.  But any AA battery holder where the batteries are in line is an example of + on one to the - on the other.    The + on the last battery goes to the load, and the - from the load goes a back to the - on the first battery.  

 

Still, take advice from those more knowledgeable than I...but chaining batteries to gain voltage is everywhere. 

 

-Brian



#18 TelescopeGreg

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Posted 28 July 2021 - 03:59 PM

Nope...no shorting.  + to - on the same battery will short.  But any AA battery holder where the batteries are in line is an example of + on one to the - on the other.    The + on the last battery goes to the load, and the - from the load goes a back to the - on the first battery.  

 

Still, take advice from those more knowledgeable than I...but chaining batteries to gain voltage is everywhere. 

 

-Brian

Yes, with batteries.  But use some caution if the "battery" is a power supply.  They're ok as long as the individual supplies are totally isolated from each other.  Most are, but I've seen some that ground the negative side to the ground pin.  Stack those and you're asking for trouble.


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#19 jeffsuth

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Posted 28 July 2021 - 05:49 PM

I explained it poorly, but I do understand that the chaining works with batteries. Like TelescopeGreg mentioned more concisely, my concern is if the individual supplies are isolated or not, as if they share a common ground, poof!



#20 jeffsuth

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Posted 28 July 2021 - 05:51 PM

Years ago I built a power supply for my "Cookbook" CCD camera that required an assortment of different voltages: -15VDC and +15VDC filtered for the camera electronics, 5 amp adjustable 0-6VDC current for the Peltier element, and 12VDC for the cooling pump/fan. The unit (described in the CCD Camera Cookbook) is quite simple and based on AC transformers, bridge rectifiers and filtered by electrolytic capacitors, and a power transistor (2N3005) and voltage regulator (LM317T) for the regulated current:

 

attachicon.gifDSC00785.JPG

 

I should assume something similar could be set up to match your requirements.

 

Per Erik

This is a great tip! I'll do some more reading on DIY CCD PSU's!



#21 don clement

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Posted 28 July 2021 - 05:58 PM

Years ago I built a power supply for my "Cookbook" CCD camera that required an assortment of different voltages: -15VDC and +15VDC filtered for the camera electronics, 5 amp adjustable 0-6VDC current for the Peltier element, and 12VDC for the cooling pump/fan. The unit (described in the CCD Camera Cookbook) is quite simple and based on AC transformers, bridge rectifiers and filtered by electrolytic capacitors, and a power transistor (2N3005) and voltage regulator (LM317T) for the regulated current:

 

attachicon.gifDSC00785.JPG

 

I should assume something similar could be set up to match your requirements.

 

Per Erik

Good job totally analog. BTW I still have my cookbook Camera.



#22 gregj888

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Posted 29 July 2021 - 10:07 AM

I too still have a cookbook CCD... I also have most of a SW cryo camera that used a mix of off the shelf supplies and a similar setup, depending on the supply.  You may be able to find a schematic for the SW on line (??).




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