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Joshua Martin (Mr_)

Post Number: 60
Registered: 1-2006
 Posted on Thursday, April 6, 2006 - 12:51 am:

My problem is a have a 16 volt 3 amp power supply and want to lower the voltage to a 12 volt to 14 volt range,I need it simple as possible and not lose alot of amprage .

(Message edited by MR._ on April 5, 2006)

Alexander N Roberts (Whoo_mythbusters)

Post Number: 71
Registered: 9-2005
 Posted on Thursday, April 6, 2006 - 3:48 pm:

Possibly a varible resistor but to go down 4 volts without losing many amps is difficult because that is what resistors do is resist current, you may just want to look around for a different power supply.

Simon Quellen Field (Sfield)
Senior Member

Post Number: 1148
Registered: 12-2004
 Posted on Thursday, April 6, 2006 - 3:54 pm:

This is a common desire that has a simple answer.
It is why voltage regulators were invented.
Take a look at the LM340T-12.

Joshua Martin (Mr_)

Post Number: 61
Registered: 1-2006
 Posted on Thursday, April 6, 2006 - 5:24 pm:

How stupid of me it's AC not DC sorry about that.Also the target voltage could be much less like 8 volts .
Thanks

Alessandro (Alessandro)
Intermediate Member

Post Number: 49
Registered: 2-2005
 Posted on Thursday, April 6, 2006 - 7:23 pm:

Do you required the output to be AC or are you just saying that the input is AC? If it is the latter the voltage regulator would still work, you just have to rectify the AC will a diode or a bridge rectifier.

Joshua Martin (Mr_)

Post Number: 62
Registered: 1-2006
 Posted on Thursday, April 6, 2006 - 11:54 pm:

The transformer's Output is AC and my need is AC.Could there be some sort of voltage divider that a a low loss of amprerage? Could I somehow use a zener diode but where could I find one rated at 3 amps?
Thanks.

Joshua Martin (Mr_)

Post Number: 63
Registered: 1-2006
 Posted on Friday, April 7, 2006 - 1:55 am:

My Output is AC and AC is what I need,could I put A smaller 1 watt zener diodes together so it can handle that power? Is there some sort of voltage divider circuit?

Joshua Martin (Mr_)

Post Number: 64
Registered: 1-2006
 Posted on Friday, April 7, 2006 - 1:57 am:

The only type of voltage regulators they have at radioshack are only one watt.

Simon Quellen Field (Sfield)
Senior Member

Post Number: 1149
Registered: 12-2004
 Posted on Friday, April 7, 2006 - 10:54 am:

If you want to convert AC at one voltage into AC at another,
all you need is a transformer.

Since you have 16 volts and you want 8 volts, use a transformer
that converts 220 volts to 110 volts. These are easy to find,
as they are used to convert European current to U.S. current for
travelers with hair driers and battery chargers.

Michael (Michaelt)
Intermediate Member

Post Number: 24
Registered: 12-2005
 Posted on Friday, April 7, 2006 - 12:09 pm:

Some of the better ones also convert the frequency-- AC is not necessarily always at 60Hz. In the US, it's 60Hz, in most of Europe it's 50Hz. If you have an application that requires a specific output frequency, make sure you get a cheaper one that leaves the output frequency the same as what is input.

Servicemen and travellers would often be embarassed by showing up late for formation or meetings because their cheaper travel adaptors provided their electric clock with the proper voltage, as the clocks ran slowly due to the improper frequency. In response to this problem, better ones were made that would also modify the output frequency to 60Hz from the 50Hz input. What this means is a more expensive convertor will actually have 20% higher output frequency than what it was fed. This can present problems if you are relying on a certain frequency.

Senior Member

Post Number: 133
Registered: 4-2005
 Posted on Friday, April 7, 2006 - 8:43 pm:

The conversion circuitry would however not function properly (if at all) since it's internal power supply would be expecting 220V at the input, therefore most likely resulting in no output whatsoever, because internally it would be converting the 220V AC to DC, then feeding the output via a wave shaper, driven by the conversion circuit.

If you aren't worried about size, and there is no internal regulator in the power supply you are using (very unlikely because it's AC), what about a Variac?

However, of course, by the time you invested in all of this, it would be cheaper to just get a suitable transformer that puts out the voltages you need.

Senior Member

Post Number: 134
Registered: 4-2005
 Posted on Friday, April 7, 2006 - 8:45 pm:

Let me clarify - Frequency conversion circuitry. A 'normal' 220 to 110 converter that is simply a transformer would probably work fine, as Simon stated.

Joshua Martin (Mr_)

Post Number: 65
Registered: 1-2006
 Posted on Saturday, April 8, 2006 - 3:17 am:

I will try the transformer idea also would a SLA battery work?

Simon Quellen Field (Sfield)
Senior Member

Post Number: 1153
Registered: 12-2004
 Posted on Saturday, April 8, 2006 - 1:25 pm:

A Sealed Lead Acid battery produces direct current.
It is not used for converting 16 volts AC into 8 volts AC.

Senior Member

Post Number: 137
Registered: 4-2005
 Posted on Saturday, April 8, 2006 - 7:50 pm:

Yup, best to learn a bit more about basics before going on... I will say this however, that on some occasions, depending on what you are powering, particularly with a device that accepts AC for an input, there may be a bridge inside, making everything DC. You'll know if you feed it DC and it doesn't do anything, yet the source gets toasty trying to feed it. Don't leave the juice on if you feed an 'AC' device 'DC'. You'll only do damage. If it DOES work however, you can be sure that you are going through a bridge, which is likely then regulated... Dig deeper. You may find (in fact likely will find) that your device wants DC after all... Just determine what it wants, and feed it ;)

Joshua Martin (Mr_)

Post Number: 66
Registered: 1-2006
 Posted on Sunday, April 9, 2006 - 1:08 pm:

I called the maker of the kit and it can take in dc and ac and foun a power supply that would work lying around.

Joshua Martin (Mr_)

Post Number: 67
Registered: 1-2006
 Posted on Sunday, April 9, 2006 - 1:10 pm:

Also there is a bridge rectifier in the kit .

Joshua Martin (Mr_)

Post Number: 68
Registered: 1-2006
 Posted on Friday, April 21, 2006 - 1:43 am:

Could I also use a solar panel charge controller right ?.Would it see a load as a uncharged battery ?

Senior Member

Post Number: 153
Registered: 4-2005
 Posted on Thursday, April 27, 2006 - 9:16 pm:

You'll probably find (although I am not sure) that depending on the type, it will do anything from simply shut down when the voltage 'floats' up toward the input voltage (from lack of load), to shutting down from over-current if the device draws too much power.

Solar regulators are designed with a battery and solar cells in mind, and will likely not make very good power supplies directly, without the battery there to deal with the fluctuations of power that the regulator is expecting (clouds, etc). Granted, using a power supply instead of a solar cell to provide power to the regulator would get rid of fluctuations in input.

Who knows, if you can supply 12v at 3 amps to the device you wish to power, and there isn't much variation in it's requirements, it may work just fine.

You still however have the problem that your device wants AC for a supply, right? (or did I miss something... heheh) - last I checked, a solar controller was strictly DC output, unless you have an inverter on it, which would be a whole different story.

Joshua Martin (Mr_)

Post Number: 69
Registered: 1-2006
 Posted on Sunday, April 30, 2006 - 10:10 pm:

I asked the mfg of the kit and it's ac and dc .

physics boy (Physicsinaction)
Intermediate Member

Post Number: 33
Registered: 7-2006
 Posted on Thursday, December 28, 2006 - 6:26 am:

Can anyone tell me is there any voltage regulator that can regulate voltage from 10 to 15 volts to 8.5 to 9 volts about 0.5 amp.

Also do voltage regulator consume more power when regulating voltage from high voltage or from peak voltage to desired voltage then it consume energy while regulating voltage from relatively low voltage.

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