Boost 5V (4.7v) to 9V

tim687 over 10 years ago

I've got a 5V (4.7v) powerbank, and I need 9V to run my Arduino and the dc motors.

I couldn't find any circuit online.

Can somebody help me?

Thanks in advance,

Tim

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jw0752 over 10 years ago +1

Hi Tim, How about a boost converter like this? http://www.ebay.com/itm/DC-DC-2A-Adjustable-Boost-Power-Supply-Converter-Step-Up-Module-2-24v-Input-New-/161650445447?hash=item25a31e0c87 John Cheaper to…
mcb1 over 10 years ago +1

Tim John is quite right. There is one thing to consider though. You haven't specified what the ratings are for the 9v motors. All motors will tend to draw twice the running current when starting, and this…

shabaz over 10 years ago in reply to tim687

Hi Tim,

That helps, looks like it probably doesn't need more than a couple of amps at maybe around 4.5-5V to run those. 9V is probably too high for the motors, maybe? Could you test by directly connecting the motor to a 4.5V battery (e.g. 3 AA alkaline batteries) or a 5V DC supply, and see if it is adequate?

For the H-bridge circuit, check out something like L293D (the D suffix version is important, otherwise you need additional diodes), e.g. see here: https://learn.adafruit.com/adafruit-arduino-lesson-15-dc-motor-reversing/overview
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mcb1 over 10 years ago in reply to tim687

Is a 10uF capacitor rated at 50V big enough for the whole?

The rough rule of thumb is 1000uF per amp ... for power supplies.
I'd suggest 4700uF for each amp the motor draws.

The 0.1 are necessary to stop the higher frequency spikes, somethign the large capacitor doesn't do.

Mark
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Problemchild over 10 years ago in reply to mcb1

I'm fairly sure those motors are a 3-6V type anyway so why do you need 9V(obviously you will have Volt drop across the H-Bridges) also you will need to be sure of the load ( a couple of amps each peek maybe reasonable even if they are only at a few hundred ma most of the time). finally you may consider a separate supply to your Arduino to keep the motor noise off the Arduino's supply.
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