How specific is 8.4v 1.6a?

You need something that supplies about 8 to 9 volts and can deliver up to

1.6 A (or more).

Power supplies are normally voltage sources. The voltage rating of a power supply is the actual value, and the amperage rating is the maximum that the power supply can produce. The actual amperage depends on the load.

That looks like cheap junk that probably cant supply even 1 amp let alone

1.6amps.. All you need is a 9v transformer with at least a rating of 1.5 amps.

- Mike

>

It appears from the picture in the auction That you need a 8.4V center positive 1.6a DC SMPS.

If you use a transformer / SMPS that wasn't designed for it you may have to worry about the barrel connector not physically fitting, and the polarity being wrong.. (ie.. center negative) but you could overcome this with a pair of wire cutters and the original barrel connector off your non wroking transformer / SMPS.

This should work if you cut the end off and put the proper barrel connector on it and it's only $9.81 +shipping...

This one might work without any modification..

- Mike

That's a little unfair, Michael. It will contain a switch mode power supply, and I see no reason at all that it shouldn't produce the 1.7 amps or whatever, that it claims. Many of the little switchers that are sold as replacement items for specific ones, come from China. I have used quite a few, and have found them to be perfectly adequate. The only thing that I would say to watch out for with the 'universal' types, is that the plug that suits your camera, cannot be easily reversed. If you are going to use it just for your camera, I would recommend a spot of superglue to secure the plug, and then surrounding it with a bit of heatshrink sleeving.

Arfa

hmm.. okay.. I guess I just feel mistrust when I see a farily inexpensive power supply that has multiple voltages on it.. :)

- Mike

If you intend using a 9V adapter instead of 8.4V, that's a difference of

600mV not 400mV - which is close to the forward volt drip of a silicon diode. Of course if the adapter is AC then you would need a pair of inverse parallel diodes in series with one of the leads (that is 2 diodes in parallel - but pointing in opposite directions) Suitable diodes might be 3A types like 1N5401 - 5408 series.

Just in case if you didn't understand that.. He is simply saying that if you use a diode inline with the transformer it will drop the voltage about 6mv and if you use an AC transformer instead of a DC one you will need 2 diodes anyway..

-Mike

Not exactly - it appeared from the original post that an AC adapter was required but some of the subsequent posts show a DC adapter, if this is the case it will take more than a couple of diodes to make an AC adapter work (and not blow up the appliance!).

Well you'd need 4 to get true dc.. but if you only use 2 it will give you a pulsing dc current which will work without proplems on some devices.

- Mike

Mike

You are missing the fundamental concept of a switch mode power supply. These things run at a switching frequency of around 100kHz, so the output magnetics can be very small, as can the smoothing caps. This means that a very small and lightweight transformer can easily deliver 1.6 amps, whereas an iron cored tranny for operation at line power frequency would, as you surmise, be "slightly beefy".

The 0.6v difference in output voltage should be neither here nor there. If the equipment in question could not handle an overvolting this small, it would have to be considered to be a very poor piece of design work. As Ian said, if you're really concerned, just stick a 1N5401 in the output line. This will drop about 0.6v across it, getting you back to where you want to be.

Out of interest, I have a little Panasonic camera which requires 4 point something ( can't remember exactly ) volts to charge it. The original power supply got lost, so I picked up a little universal switcher at the local Maplin store, and just use it on its 5v setting. Camera is quite happy at this. Note also that any switcher that you purchase, will by nature be very closely regulated for output voltage, so yes, the answer to your question is that you really can just use a 9v supply, so long as it's a switcher, which will have exactly 9v out, on or off load.

Arfa

Arfa, I agree with you and think that the adjustable switcher would work without any probs, but I think you have me confused with the op since he didn't post his name in the reply and just left mine at the bottom..

- Mike

I would expect further regulation inside the device. 8.4 volts is not a standard supply voltage for digital circuitry. They are probably downregulating it to 5.0 volts.

We've now gotten him really confused. By "AC adapter" I think he meant "adapter to plug into the AC power line, which outputs 8.4V DC." Not "adapter that outputs AC" as the posting about multiple diodes assumes.

Mike My sincere apologies for this error. I knew that I wasn't referring to you - I just missed the fact that he had left your name on, and not put his own. I assumed that he was called Mike as well.

Again, sorry

Arfa d;~}

I have a Sony PHD-A55 Digital Picture Frame for which I have lost the ac converter. It did look quite beefy and may have been switchable? not sure about this or if there is a need for it to be switchable given the probable circuitry on this unit.

Sony says it is an 8.4v 1.6a AC-PLM3 and wants to charge me over a hundred bucks for it. To me this means 'we discontinued this model quite some time ago and don't want to have to provide parts for it any more'

I was wondering how specific these figures are, especially given that it doesn't SEEM to use much power but is meant to be left on all day?

Firstly, can I use a universal converter which has a 9 volt setting with this unit?

Secondly, there do seem to be 8.4 volt converters out there available reasonably inexpensively but they all seem to carry the magical MADE IN CHINA annotation which seems to mean 'this unit will either burn out or stop working in the near future'. They can be had on ebay for some tiny amount of money (but carry very high shipping charges)

And they don't seem to work at much more than an amp. Is it a worthwhile venture to try to use one of these options? Seems unlikely that the AC-PLM3 will come up on ebay by itself.

Ask the OP to examine the casing around the power jack for any markings that identify the power source rating and type. As long as there are any that should clear things up.

Interestingly 8.4V is the nominal terminal voltage of a 7 cell NiCd/NiMh battery!

No apologies needed.. don't worry about it ;)