Nice combo thread, and a great idea having this kind of info all in one place. Also, thanks for the acknowledgement.

6. Something that I think is relevant to EZ-B power is the following that was posted by Jeremie at EZ-Robot...

Quote:

I know it has floated around the forum that the digital power pins can handle 5 amp per digital pin, but that's not the case. It's max of 2 amps per pin and a combined constant amperage of 5A for all the digital power pins. While you can have a spiked (pulsed) current up to 20A, the ez-bv4 is only rated for 5A of constant current.

If you find you are drawing much more than this we would recommend externally powering your motors directly from the battery power supply to the motor drive electronics (it's good idea to add a fuse in between them).

Servo power is best to come from a 7.4V LiPo battery (with protection) but you'll need servos that are rated for 7.4V, if you don't have servos that can handle this high of a voltage you'll need a voltage regulator.

The thing to watch out for with regulators is how much current draw they can handle, like most motors, servo motors can draw huge spikes of current when first initialized so you'll likely want to double or triple the current rating of your voltage regulator compared to the operating current of the servo so you don't experience a brown out. Brown outs result in the voltage dropping below a certain level and will either effect the operation of the servo or the electronics controlling them.

EZ-B v4 Data Sheet

Valid tip! Thanks!

Nice Tech! Thanks for getting this together. Switching power supplies are far better than linear converters. However, it's important to know there are many different switching power supplies that will deliver both the input and output voltages you'll be needing. The amount of amps the PS will supply is also AS important. If your PS is being asked by your motors to deliver more amps than it can supply the PS will shut down. Case in point; I have a 120vac to 12vdc switching power supply that is rated at 12 amps. I tried to pull 30 amps through it from a car windshield wiper motor and it quickly turned itself off. No harm done thankfully because it had a protection circuit. A simple power cycle got it running again.

So, if you're shopping for a switching power supply please do your homework. Find out what your max amp draw will from the motors you're using, what voltage (3.3v, 5v, 12, exc) and voltage type (AC or DC) they need and what voltage and type your plugging the PS into. This is the only way to choose the proper PS you need.

Finding one to buy after you know your numbers is another issue. I like to use Mean Well power supplies. Very well built and they offer a wide selection. Here is the master list of Mean Well AC-DC converters:

distributor.meanwellusa.com/webnet_usa/search/seriessearch.html

One more thing; @Steve mentions above and others have echoed that Lipo batteries are best for servos. I'm still not a believer in that theory. I don't have a single battery on my full size B9 Robot and have many High Power, regular and micro servos and a number of big DC motors. I have never had an issue with brownouts when any of them have started up or while they run. The trick is to get a PS and wiring that will handle the MAX power draw. Also as Steve mentioned correctly above, when supplying power to a big motor or servo that it's important to bypass the EZB and power the motor directly from the PS, Do not use the EZB as a power conduit.

Have Fun!

Hey Dave.

I just wanted to say, although LiPos are great for powering servos, I don't actually use them much now, and use NiMH packs as you can charge them while still operating a device (depending on amperage) which are great for low power "monitoring" modes such as security. As are bench supplies which I'm all for as well, as there are lots around that deliver good amperage for a great price. Great for static robots such as your B9 and for bench testing.

I haven't got around to it yet, but after helping Will out looking for a supply for his Alan head project that you may remember, I discovered very reasonabley priced mains power supplies delivering 20, 30, 40 amps and plan to get one myself for testing.

You also make very good valid points about switching supplies too. Very useful Information to know.

Sounds great @Steve. I guess it really depends on your application and how you want to be using your robot.

Another thing I've learned about these power supplies is that as you choose units (within a curtain model number) with higher output voltages your available amps goes down. So you will have one unit that delivers 7.5 vdc and provides 40 amps and another that will deliver 12 vdc and only be able to supply 27 amps. You would have to go to a different model to get the higher amp capacity and it would probably be physically larger and more expensive. Like everything else in life.

Cheers!

I have two of the Mean-Well power supplies arriving today...let you know how it goes.

Often desk top robots are built and the need of a battery to power it seems un-needed, and a power supply would work best. Almost everyone has an old pc around. Most pc power supplies can supply 12vdc @ about 20 amps. I want to know how to get this supply to run an EZB v4 and EZ robot servos and not burn them out. If a regulator is needed, could one of you electronic guru's advise us what to use or how to make one.

Ron R

@Ron.

A 12v 20 amp supply would run an EZ-B no problem, but the EZ-Robot 7.4v servos connected to that 12v EZ-B wouldn't like it very much. You could power each servos through a drop down buck converter or linier regulator with an output voltage that matches the servos, but more importantly, the amp output would have to match too, to handle the servo inrush current and maximum holding torque. Supplying 20 amps to a servo is not a problem, as the servos will only take what current they need.

When using a step down converter or regulators, as well as output voltage, is the amp output too. You could be supplying 12 volts and 20 amp input supply through a 6 volt regulator for example, but if that regulator is rated for 3 amps output, that's all your servos will get... 3 amps which may not be enough for a servo. So you would need a buck converter or regulator that matches you voltage needs, but with a much higher current output.

In the first post in point 3, there are some links to some good 7.5v power supplies with high amp outputs.

One think to keep in mind, is when using a power supply, a linear power supply can stubble to supply their specified amperage which is a limitation to how these supplies are designed. Digital switching power supplies like the one I linked to below, and like the ones some computers use, are far better.

www.trcelectronics.com/View/Mean-Well/SE-200-7.5.shtml

Or for a high amp regulator..,

www.amazon.com/gp/product/B000MXAR12/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1