Power Supply

 
#1

Hey guys I'm not lumping this into the ALAN thread so it can be used for others looking for a source.

I have been overwhelmed by people contacting me about ALAN and what tiers will be offered. Alot of folks are expressing interest in a development kit with everything you need including all the servos, etc to build ALAN. Originally I designed him to be wireless so you could take him on the road..lol, but in the end the lipos, charger are pretty expensive for the amperage needed. We also have interest in the academia circuit and we need ALAN'S that work all day in the class room and need to be plugged in. I currently use a workshop power supply that delivers 30 amps and variable voltage. ALAN was designed to run on 7.4 volts. There are just too many issues with a customer using a variable voltage choice as in .i.e. blowing up everything if the voltage is set too high, etc.

So I'm in the market for fixed voltage...(seems 7.5v is used in the medical field), ac/dc PFC (for europe friends), 115/220v, 30-40 amps power supply. Prefer a small form factor but i cant find any. And under $100 USD. Lets see if you can help me find a vendor. I found some from Jameco, but they are larger, like rack mount (8 x 4 x 2 inches)

#2

Hey will.

I had a bit of a search for you, and came up with the following fixed voltage supplies which was all from one website called TCR Electronics and are all under 100 bucks. Searching other sites pretty much came up with the same makes and models. The ones I've linked to are the best of the bunch that I think meet some of your requirements. I threw a couple of 20 amp supplies in as well in case anyone else is looking...

7.5v
40 amp
345 watts
215x115x50
$44.80 for 1 to 9 units (cheaper after that).
www.trcelectronics.com/View/Mean-Well/SE-350-7.5.shtml

7.5v
40 amp
300 watts
199x105x41
$76.50
www.trcelectronics.com/View/Mean-Well/HRP-300-7.5.shtml

7.5v
20 amp
150 watts
199x99x50
$43.90
www.trcelectronics.com/View/Mean-Well/SP-150-7.5.shtml

7.5v
20 amp
150 watts
199x99x30
$36.90
www.trcelectronics.com/View/Mean-Well/RSP-150-7.5.shtml

7.5v
32 amp
240 watts
190x93x50
$50.90
www.trcelectronics.com/View/Mean-Well/SP-240-7.5.shtml

And the smallest I found at a reasonable price, but at 20 amps...

7.5v
20 amp
150 watts
159x97x38
$47.70
www.trcelectronics.com/View/Mean-Well/HRP-150-7.5.shtml

Anything smaller in the way of form factor, and you're looking to pay out at three digit figures. The one other plus about this website is that they do bulk buy discounts too.

Im not sure if this is the type of thing you're looking for, but I hope it helps. Smile

Steve.

#3

Steve has selected a good choice of PS's for you. Stick with the Mean-well. There are a lot of cheap knock-offs out there. Mean-well is a solid, well built and true "switching" PS. You can go to their web site and search through a simple list of the PS's they offer and pick the one that will work best for you. Just make sure you pay attention to the AC input value. They offer 120v input, 240v input and units that use either by selection.

Mean-Well Power Supply web site

Prices are all over the board for the same PS. More so when your looking for a special PS that will supply lots of amps. I've found that I can usually get the best price by far at Online Components. However although they offer a return policy they are very strict and will reject it and send it back to you if it looks like it's been used (however that's another story for a different thread) :

online components web site

Good luck Will,
Dave Winky

#4

Thanks Steve and Dave. I had just come across Mean Well PS last night. They have a really good price per amps. Their voltage input is an odd assortment of numbers ranging from 88 upto like 280 volts in one unit. I assume there is some kind of internal switcher? I'm going to order the 7.5v 40 amp version and see how it petforms. I wish they came in a smaller form factor but I can always 3d print a nice case for it.

I'll check thru all of Steve's links too see if something has a better visual appearance.

As always, thanks for all the help. We are crawling to the finish line to get Alan out to the public. I need to dust off that cloning machine and start building a factory of workers Smile

#5

Wow TRC has some of the best prices! Great find Steve!

#6

No problem Will. I figured I'd take on the challenge and it made for an interesting search. It's just a shame the smaller units with the right voltage and amperage requirements or sooo expensive. I found one that was about 100x40 or something and it was about $400... Ouch. And like Dave said, there is a lot of rubbish out there that promises the earth at a great price but have really poor reviews.

Anyway, your more than welcome and I hope you find something that's suited for what you want.

#7

As far as the voltage input being an odd assortment of numbers; on the model you are going to try (HRP-300-7.5), as long as your input voltage is AC and within that range you will get 7.5 volts DC output. The internal rectifiers and other components will take any voltage within the stated range and magically transform it into 7.5 vdc. Presto Chango!

Sometimes you'll find a PS that needs to have jumpers set or a switch moved to select the proper input voltage. The model you've selected looks like it does it on it's own. Smile

#8

Sweet! Thanks Dave!

#9

Just to be clear Will, the other 40 amp Mean-well (SE-350-7.5, the less expensive one) has the input voltage selectable by switch. Looks like this model was designed for the North American customer. This means that you can operate it either on the North American 120vac system or the 240vac system. You just have to set the switch in the proper location and have the AC connections attached properly. Most likely your always going to want the 115 setting. You can then wire it directly into your house wiring that powers your TV and light bulbs (one positive leg, one negative leg and an equipment ground). Most all American home or business also has 240 vac voltage. Some people run heaters, cloths dryers and electric ranges off this voltage. You'll have two opposite positive legs and an equipment ground. If your selling these internationally you may want to choose the HRP-300-7.5 as it is Universal Input.

Off Topic: Here's a couple fun facts; it's much less expensive to run equipment from 240 vac then 120 vac because it's more efficient. I have 240 vac forced air heaters installed in the walls in my finished basement and I don't really notice any rise in my power bills in the winter. Smile
Not sure of exact dates but back in the late 1800's and early part of the 1900's till 1950 most American residential homes were supplied only with 110 vac. In mid century when the power companies needed a way to sell their excess power and needed different ways to generate revenue, they embraced the new 240 vac appliances coming to market. They not only started running the extra wires on the power grid needed for the new secondary voltage but also started selling the new appliances to consumers that uses it. Now in the year 2015 in the mid-west most homes are finally almost all rewired to accept 240 vac. However now and then in the inner city we still find a home that is wired to only accept 110 vac. *sick*

#10

Thanks Dave on the power supply. I wanted to make sure what ever I buy had dual voltage as these will be included with the Alan android head, and will most likely ship to US and Overseas and wanted to make sure I was covered!

Very interesting on the home power. I never knew that! And I grew up in my grandfathers motor rewind shop and electrical contracting businesses. When I was a teenager I would run wire for commercial and residential homes during summer breaks. learned quite a bit. I then transitioned into the rewind shop, tearing down motors from a nearby factory. They ran on various voltages. Our largest motor I worked on was big enough to stand inside the stator, arms outstretched to touch the windings! Good times.