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9v power supply

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antonm

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I'm sure you must all be thinking "oh no, not another one", and I'm sure that somewhere on this forum there already is exactly what I'm looking for -- I'm just not confident that I've found it. I would be very grateful if someone would please guide me.

I have a small wireless IR video camera and receiver (for bird nest watching), both of which work fine off small 9v batteries, but don't want to work very well with off-the-shelf all-things-to-all-people multivoltage transformers (the batteries don't last much over 4-5 hours, unfortunately). I know that I have the (+) and (-) the right way around, BTW! I think that these cheap transformers are probably quite noisy, and I think I need a clean, regulated 9v power supply. I think I need a transformer-rectifier-smoother-regulator, but I'm not sure if those 4 components alone will do the trick.

Search came up with this one which looks like it would fit the bill, but from all the posts following the first one in the thread, I don't know if the original circuit is what everyone agreed in the end it should look like.

I would be most grateful for any help, please.

PS. I'm also considering using solar cells (4-5 mini-panels each providing 2v and 150mA) to run the camera (output power 200mW at 8~9v) -- is this likely to be a goer? or a waste of time?
 
That would do the job even though it might be a bit overkill.

Solar cells are often rated for tropical sunlight at mid-day, I would half the output of those cells. Also use the solar cells to charge a battery and then you'll have power all of the time.
 
antonm said:
I have a small wireless IR video camera and receiver (for bird nest watching), both of which work fine off small 9v batteries, but don't want to work very well with off-the-shelf all-things-to-all-people multivoltage transformers (the batteries don't last much over 4-5 hours, unfortunately). I know that I have the (+) and (-) the right way around, BTW! I think that these cheap transformers are probably quite noisy, and I think I need a clean, regulated 9v power supply. I think I need a transformer-rectifier-smoother-regulator, but I'm not sure if those 4 components alone will do the trick.

If you use a solar panel, you will require a re-chargeable battery, 12V sealed lead acid [SLA]. Many solar panels are wired to give a charge output suitable for a 12Vbty.
The power rating of the solar panel and battery will be determined by the power consumption of the camera system. I expect you only run the camera during daylight ? [indoors or outdoors?]

The reason why I am suggesting a SLA battery powered system is avoid running long lengths of cable and the safety aspect regarding mains power.

You could have a low drop out 9V regulator located within a box housing the 12V battery, this would give the very 'clean' supply you are looking for.

The solar panel would keep the 12Vbty topped up, subject to the rating requirement of the system.
It would be possible to build a small mains driven battery charger and also mount that within the battery box, for those times when the sunlight is limited.

PS. I'm also considering using solar cells (4-5 mini-panels each providing 2v and 150mA) to run the camera (output power 200mW at 8~9v) -- is this likely to be a goer? or a waste of time?

Lets know the power requirement of the camera system
 
Thanks, Hero999 and Eric.

The only info I have on the camera is its output power (200mW at 8~9v) -- I don't know how that relates to its input power requirement, except that it will drain a small 9v alkaline battery within 4-5 hrs, IIRC. I had planned to use it in daylight hours only, but of course your solutions make dark-hour running possible.

Rapid has a selection of SLAs ranging from 0.8AH to 24AH -- would something like 1.2AH do? My (amateur) figgerin' says 200mW @ 8v requires 40mA, and a 1200mAH battery could churn that out for 30 hours (but internal losses would increase power consumption). Since I'm not likely to run the system all the time, that sounds pretty good?

And would the 5x2v solar minipanels in series be enough to recharge it? Do I simply attach them directly to the battery terminals? surely a diode needs to go in there somewhere?

Thank you both for your help!
 
antonm said:
Thanks, Hero999 and Eric.

The only info I have on the camera is its output power (200mW at 8~9v) -- I don't know how that relates to its input power requirement, except that it will drain a small 9v alkaline battery within 4-5 hrs, IIRC. I had planned to use it in daylight hours only, but of course your solutions make dark-hour running possible.

Borrow a test meter and measure the actual current into the camera, lets know.

Rapid has a selection of SLAs ranging from 0.8AH to 24AH -- would something like 1.2AH do? My (amateur) figgerin' says 200mW @ 8v requires 40mA, and a 1200mAH battery could churn that out for 30 hours (but internal losses would increase power consumption). Since I'm not likely to run the system all the time, that sounds pretty good?
It sounds OK, but check the camera current first.

And would the 5x2v solar minipanels in series be enough to recharge it? Do I simply attach them directly to the battery terminals? surely a diode needs to go in there somewhere?
NO, 10V will not charge a 12v battery, you should get a 12V solar panel that is designed to charge a 12V SLA.
Thank you both for your help!

As soon as you know the camera current, you can use that as starting point to calculate the battery capacity, the solar panel watts [12Vnom] and also the rating of the 9V regulator.

Lets know the camera current and we can do some sums.
Regards
 
Thanks for that, Eric. The missus says my old kit is somewhere on the loft, so I'll dig that out.

Will an off-the-shelf all-things-to-all-people multivoltage transformer set to 12V charge the SLA (taking it indoors and doing it overnight), rather than buying more solar panels? I have one of those transformers, so wouldn't need to buy one.
 
antonm said:
Thanks for that, Eric. The missus says my old kit is somewhere on the loft, so I'll dig that out.
Understood

Will an off-the-shelf all-things-to-all-people multivoltage transformer set to 12V charge the SLA (taking it indoors and doing it overnight), rather than buying more solar panels? I have one of those transformers, so wouldn't need to buy one.

When you say 12V transformer, do you mean 12V charger?

A bog standard car battery charger is NOT suitable for SLA charging.
If you have a standard battery charger, you could buy a low capacity car battery instead of the SLA. At such low power requirements as the camera has ie: say, 25 to 50mAmp a S/H car battery would get the job done.
EDIT:
A decent car battery say, 30/40A/hr would power the camera for a week also an Infra red source for night viewing,
 
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No, it's one of those wee power supplies for radios and tape recorders -- cost a couple of quid in Tesco -- the "mains" part of the blurb on your gadget which says "battery and mains". "Transformer" is probably the wrong word -- "9v power supply" is probably better -- but I would expect that this forum attaches a far more technical meaning to that phrase! I#ve read that theyu are horrendously noisy, and often put out a far higher voltage than they specify.

I wasn't thinking of using a car battery. The camera is only about half a matchbox in size, maybe a bit less, with a wireless range of 150m. I'd like the thing, battery included, to fit in the palm of my hand, more or less.

The camera actually has 6 IR LEDs built in, and it works a treat in the dark. It's quite nifty for a wee gadget like that!
 
Have you tried 8 AA NiMH batteries in series, 9.6 volts. Should last considerably longer than a single 9 volt battery. R/C cars somtimes use 9.6 volt NiCad packs, the charger should work. Solar... Depends, going to need a good size panel to charge the batteries, and provide power during daytime viewing. Just guessing that you want to check on the nest anytime, not just at night. Use to be some cheap panels for keeping a car battery charged, if it's going to be sitting for a while. They go for around $15.00. Think I can get you a link to one I got a while back...

https://www.goldmine-elec-products.com/prodinfo.asp?number=G16130

Not sure if that will be enough, heard it rains almost everyday over there...
 
Could you give us more info on the multivoltage transformer? Is it regulated? Linear or switching? 9V should be 9V and if it doesn't work then there's something that it's doing that's no bueno.

ETA: I just realized you may have meant multivoltage as in the input, ie 100-240V wide ranging. In that case it's probably a switcher. Any other specs if that is so?
 
you could easily use solar panels to charge a 1.2 AH. i have seen some cheap 12 volt solar panels for about $30. maybe you could hook 2 up in parallel to get more current out of them. i think they supply around 140 milliamps each. i think 280 milliamps at 12 volt will charge that battery?
 
speakerguy79 said:
Could you give us more info on the multivoltage transformer? Is it regulated? Linear or switching? 9V should be 9V and if it doesn't work then there's something that it's doing that's no bueno.

ETA: I just realized you may have meant multivoltage as in the input, ie 100-240V wide ranging. In that case it's probably a switcher. Any other specs if that is so?

hi,
Is this post in the wrong thread??

What multivoltage transformer?
 
speakerguy79 said:
First post, second paragraph, first sentence, third clause :)

hi speakerguy,
>>>
I have a small wireless IR video camera and receiver (for bird nest watching), both of which work fine off small 9v batteries, but don't want to work very well with off-the-shelf all-things-to-all-people multivoltage transformers (the batteries don't last much over 4-5 hours, unfortunately). I know

The way I read it, he hasn't got a , but don't want to work very well with off-the-shelf all-things-to-all-people multivoltage transformer:confused:

Regards
 
Er, yes, I have 2 or 3 of those transformers -- all take ~220v AC input and have a sliding switch to pick an output voltage of 3v, 4.5v, 6v, 9v and 12v DC. Obviously very noisy, probably barely qualify as DC -- when I have the receiver running off its battery and plugged into the TV, it's fine, but if I run it off the transformer, there's a loud hum, and sometimes it doesn't want to produce a stable image. So, I doubt that it's regulated, and may actually damage the kit.

I'm actually trying to do this for a modest outlay, and more for fun that out of any fiercely ornithological drive.

I have an idea that my cheap-and-cheerful transformer would probably charge a SLA battery, because the battery probably won't mind too much if what it's being fed is a bit noisy and maybe a tad more than 12v -- is that right? I would just need to know if I can simply attach the 12v transformer directly to the SLA's terminals, or do I need any other components?

For what it's worth, here are images of the camera and receiver.

IMG_0743a.jpg IMG_0744a.jpg
 
If it's unregulated those things can be 50% higher at no load voltage. If your device pulls a lot less current than the supply can do, maybe try it on the 6V tap?;) Or you can set it to 12 and just put a 7809 wired point to point in the cord somewhere, then wrap it up.
 
antonm said:
Is a 7809 a regulator?

hi antonm,
I think you should decide, do want to charge a 12V SLA battery from one of the 'budget' DC psu's or do you want to regulate the output from a 'budget' DC psu down to +9Vdc???
EDIT: there is no guarantee that the 7809 will kill the 'hum' when using this with the psu. The hum could be caused by other problems, I use the bog standard 12V psu on all my security camera's without any problems.

A 12V SLA requires a float charge maximum voltage of +13.8V, if the battery is to be permanently connected or a cyclic charge of +14V maximum, if charged up then disconnected from the charger.

A discharged SLA is about 10.8V, not enough to drive a standard 7809 Vreg.

Lets know.
 
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If the supply is a switching supply the regulator might not help if the switching frequency is too high. If it is just a poorly regulated linear supply I would expect it to fix the problem.
 
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