Need 4.5 Volt 4 Amp Power Supply, Cheap

[pinball2k]

I have a motion detector that uses 3 C cells for the receiver and chime. It has a plug that is labeled 4.5 V. I tried a 5 Volt 3 Amp power supply with no success. The receiver works and the LED lights up in response to movement near the motion detector but no chime. I did some rewiring (thicker gauge wires) and can get the chime to ring SOMETIMES. I think the receiver chime draws more amps than I am providing with the power supply I have.

I found some nice boards that will provide regulated 4.5 volts but are only rated at 2 amps. I have a 6 amp 12 volt supply and was thinking of using two boards with both boards inputs wired in parallel and both outputs also wired in parallel. Will this work?

See attachment.

[budm]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Can we see some pictures? 4A is a lot of current for battery operated chime.

[srhofmann]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

If you have a 6 amp 12 volt supply I would build up a test rig using a LM317 adjustable voltage regulator. That way you can you determine the min and max working voltage and how much current is really needed.

As an aside, why not just throw a li-ion battery, like a 18650, into it with clip leads and see if it works. If you don't have any just cut open an old laptop battery pack.....

[pinball2k]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Can we see some pictures? 4A is a lot of current for battery operated chime.

See attached.

[pinball2k]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

As an aside, why not just throw a li-ion battery, like a 18650, into it with clip leads and see if it works. If you don't have any just cut open an old laptop battery pack.....

Yes, I know it seems strange but C cells are rated at 8000 mah so that makes it look ok. I looked for some 18650 and I will try these also.

I'm still would like comments on my drawing I attached. Will it work, in theory?

[R_J]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

They sell an adaptor for that and its rated 4.5 volts 1 amp https://www.amazon.com/Wall-Power-Ad.../dp/B007HOKH2I
and this one comes with the adaptor http://www.2270.pricereview.co/blog/...e-Adapter.html

[eccerr0r]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

No, drawing 4A continuously from C cells does not sound right, where did this number come from? Can you use a capacitor to help against instantaneous draw, as that thing can't possibly be drawing 17+W continuously. Does the device still work on batteries, did you measure how much current it actually draws? Three brand new C cells in series can get pretty darn close to 5V so it should well be within the proper operating range.

Something else is wrong.

[mariushm]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

A very cheap and simple trick to get around 4.5v from 5v would be to simply put a diode in series with the positive wire of the power supply.

A regular diode will drop around 0.7v and a schottky diode will have a voltage drop of around 0.35-0.5v voltage drop.

The efficiency lost is minimal, not much more than what would be if you'd use a DC-DC converter.

That device is unlikely to use more than 1A from batteries so it's not much wasted on the diodes.

[budm]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

They sell an adaptor for that and its rated 4.5 volts 1 amp https://www.amazon.com/Wall-Power-Ad.../dp/B007HOKH2I
and this one comes with the adaptor http://www.2270.pricereview.co/blog/...e-Adapter.html

I wonder where he gets the 4A rating from, I doubt that the chime needs thatr much power, something is not adding or not logical here.
BTW, that is regulated 4.5V 1A power supply, I wonder he was using non regulated linear power supply so light load Voltage will be much higher than 5V, he needs to check that 5V supply he was trying to use.
They use C cells so you do not have to replace batteries too often.

[redwire]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Box says 1-9V battery and 3-C cells, or power from 12V 1A AC adapter.

It is constantly making a pulsed IR light beam (for 400 ft. range) but no way it is 4A!

[pinball2k]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Here is why I'm pursuing a 4.5 volt 4 amp supply.
1. I am talking about the receiver only.
2. The receiver uses 3 C cells for 4.5 volts.
3. I first tried a 5 volt 2 amp supply and that did not work; meaning the signal led in the receiver flashed with motion on the PIR but no chime.
4. I them tried a 5 volt 3 amp supply I had around and that worked intermittently; meaning the the signal led in the receiver flashed with motion on the PIR but the chime worked about 2 times out of 10.
5. Yes, the device works 100% of the time with new batteries.

The reason I want to use a power supply instead of the C cells is cost. The brand new batteries lasted less than 1 month. Too much activity for battery operation.

Thanks for everyones suggestions, I appreciate the thoughts. I know my method of getting to 4.5 volts and 4 amps is non-scientific but I'm having fun trying to solve the problem. All I want is a cheap solution that also works 100% of the time.

[budm]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Are the 5V power supply regulated? Linear non regulated? Or SMPS regulated?
It is easy enough to check the current draw of the unit.

[CapLeaker]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Ali has 5V 8A PSU's for 10 CAD$.

I wonder if the output capacitor isn't big enough to handle the load on the 4 amp supply. OR the regulator isn't regulating properly.

[srhofmann]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Here is why I'm pursuing a 4.5 volt 4 amp supply.
1. I am talking about the receiver only.
2. The receiver uses 3 C cells for 4.5 volts.
3. I first tried a 5 volt 2 amp supply and that did not work; meaning the signal led in the receiver flashed with motion on the PIR but no chime.
4. I them tried a 5 volt 3 amp supply I had around and that worked intermittently; meaning the the signal led in the receiver flashed with motion on the PIR but the chime worked about 2 times out of 10.
5. Yes, the device works 100% of the time with new batteries.

The reason I want to use a power supply instead of the C cells is cost. The brand new batteries lasted less than 1 month. Too much activity for battery operation.

Thanks for everyones suggestions, I appreciate the thoughts. I know my method of getting to 4.5 volts and 4 amps is non-scientific but I'm having fun trying to solve the problem. All I want is a cheap solution that also works 100% of the time.

Just put a big cap or 2 or 3 across the output of the a single supply and see what happens......

[pinball2k]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Are the 5V power supply regulated? Linear non regulated? Or SMPS regulated?
It is easy enough to check the current draw of the unit.

Here is a link to Ebay where I purchased them.

http://www.ebay.com/itm/20W-DC-DC-4-...MAAOSwopRYeZR5

Also see phot attached.

[redwire]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Ok, so the chime is a solenoid and gong... Or a loudspeaker? A solenoid could need 4amps peak.
That Power supply module has minimal capacitance on it, which means it is a bit noisy. Battery power is extremely quiet and it may be the receiver doesn't work well with noisy power.
I would add a big capacitor at the receiver's input power - say 1,000-4,700uF to see how it does. The cap will filter some power supply noise and also give a boost when the solenoid needs it.

[budm]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

Here is a link to Ebay where I purchased them.

http://www.ebay.com/itm/20W-DC-DC-4-...MAAOSwopRYeZR5

Also see phot attached.

So it is buck converter, so all you have to do is to set the output to 4.5V and put DCA in series with + output to see how much current it draws and if it maintain 4.5V output..
BTW, what is the feeding Voltage to that board?

[pinball2k]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

I have several choices including 24V 6a power supply.

[pinball2k]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

That Power supply module has minimal capacitance on it, which means it is a bit noisy. Battery power is extremely quiet and it may be the receiver doesn't work well with noisy power.
I would add a big capacitor at the receiver's input power - say 1,000-4,700uF to see how it does. The cap will filter some power supply noise and also give a boost when the solenoid needs it.

I will try this, you may be right.

[pinball2k]

Re: Need 4.5 Volt 4 Amp Power Supply, Cheap

So far, this works just fine. Thank you srhofmann for the suggestion.

Here is what I did.
1. Purchased 4pcs 18650 3.7V 9900mAh Rechargeable Li-ion Battery +2 Charger Set High Capacity. From Ebay for $12.69 including shipping.

2. Modified one of the 2 chargers to be a battery holder.

3. Soldered a proper barrel connecter and short lead into the "battery holder".

This is working just fine. Let's see how long the batteries last.