Power Supply for Robotic Pony toy

What is your goal in this effort? To avoid buying batteries? To increase the run-time between battery changes?

E.g., you can buy two sets of rechargeable NiMH cells and charge one set while using the other.

Recall that any sort of power supply means your pony will end up tethered to a wall (socket).

[Somehow, that seems to defeat the purpose for a "motive device"]

You will need to better understand what the pony's use of the power is likely to be in different activities. E.g., when moving around, it probably places a larger draw on the power source than when "thinking" (speaking? Do ponies speak?).

And, the device's sensitivity to voltage fluctuations (i.e., with power demand) may vary with these different activities. As the power pack sags, perhaps motion just gets slower. Or, perhaps it *stops* at a certain point.

Note that the choice of battery chemistry will also affect the useful life of the battery. E.g., alkalines being better than C-Zn.

1. To avoid buying batteries.
2. It's a pain to change them.

NiCads seem to have a very short lifespan. And I'd still have to change them often.

It does NOT walk. It's meant for kids to sit on. The head moves up down left right, as well as the eyes blink, mouth moves, ears wiggle, tail swishes, and more. They are actually very real looking and hi-tech. The motion sensor makes the head turn toward you, chew, whinney, and other functions. It has a built in microphone which causes it to make sounds when you talk to it.

No, see above.

It makes all kinds of pony sounds (speaking).

Yea it just stops all functions.

It's supposed to use alkaline, but C-Zn does work too.

Fair enough. Have you measured how long ("typical use") a FRESH set of alkalines (or carbon-zinc) batteries last? This would give you a rough idea as to typical power consumption.

You can also temporarily remove the batteries connecting them to the toy with clip leads and inserting an ammeter inline to get a feel for current requirements.

Yup. Note, though, that I suggested NiMH, not NiCd's (also short-lived)

Ah, cool! Much like the Teddy Ruxpin et al. toys I've "repurposed", here. They, of course, are not intended to be mobile so sitting them in various places around the house doesn't "look odd".

I will have to explore this pony, as well!

It's hard to know if this would be more or less demanding of power than the "mechanisms" (which are often little tiny DC motors with large gear-reductions)

You might find that a smallish 9VDC wall wart or brick, coupled with a bulk capacitor located IN the toy, will allow you to handle the peak loads (from the cap) as well as the average loads (from the appropriately sized wall-wart). Note that it's relatively easy to come by 12V power packs capable of several amps (e.g., for LCD monitors). Once you fall below 12V, things get a bit trickier (as lower voltage products tend to also require lower power)

[You may need some high frequency decoupling at the toy end, as well, if the supply oscillates]

Finally, you might also consider a "9V battery charger" located outside the toy and tethered to the *batteries* within! The idea being that it tries to keep recharging the batteries in the toy while allowing them to handle the "real load" (depends on how heavily the toy is used "per session")

I have a toy that fires foam darts using a spring-loaded piston pump it runs off 6 D cells, at some ridiculous current.

a linear regulator with a heatsink good for 9 to 15 watts... oh hang on you said CB so it's probably 13.8V out make that 15 to 25 watts.

ballpark 5A for primary cells 20A for rechargeable.

yeah, that would be a good start.

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umop apisdn

9V 5A is not uncommon for a compact switching power supply. Any online electronic components store will have a hundred to choose from.

I recommend one with proper EMI shielding and a ground. Many "your brand here" switching power supplies leak dangerous amounts of RF and line power.

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Thanks for the help. Maybe a combination of NiMH cells and an external charger would be the ticket. I know I can sneak a wire into the removable battery compartment with only a small hole drilled into it.

I have not measured the length of time the bateries last, but I know the alkaline last a little longer then carbon zinc, but not that much longer. I usually buy what is the cheapest, normally C-Zn, which are half the price. I'd hate to have to buy batteries for kids, who left it turned on all the time.

It just sits in my living room and looks cute. It seems adults like them as much as kids, if not more. There are videos of them on youtube, in action. Just type in "Butterscotch pony" or "Smores pony" (Smores is a different color, but does the same thing). They are in the "Fur Real" series of animated robotic animals made by Hasbro. Unfortunately Hasbro discontinued these large ones and only make small ones now, so parts are no longer available. They sold for $300 or more in the stores around

2006 to 2009 or so, and I see them sold (used) for as much as twice that amount on ebay now. I bought mine at a garage sale for only a few dollars and was shocked they sold it so cheap. Aside from a missing ear, it was complete and worked. I just cleaned it up and it's been a wonderful decoration and conversation piece ever since. I keep looking on ebay for a replacement ear, so I see what they sell for. Why Hasbro stopped making them makes no sense to me. They are one of the coolest toys ever made.

BTW, it's about 3 feet tall in height and about the same size as a

*real* Shetland pony.

There is a website that shows how someone turned one of them into a "fire breathing" robot. To me, that is a waste of such a great toy, and dangerous, but their site shows how one of them is built with photos of the inside as well as the micro processor computer board within. That site has been helpful to know how it works though......

I have no idea as to your technical ("theory") ability. But, this isn't JUST "sticking a charger on the batteries while in use". You need to consider what sort of use they will see in that configuration (and whether you will confuse the charger as it expects to see the cell voltages INCREASING as it charges them, not decreasing from the pony load!).

Design should have included a "sleep" mode.

Yes, I've done similar with the WoW toys (Ruxpin et al.). As they aren't intended to be mobile, they just sit in various spots in various rooms and act as animated speakerphones (a blatant rip-off of a COTS toy I saw at CES 20+ years ago). I'll be re-hacking them to tie them into my home automation system as they'll have more value, there (and see more use as well!)

My WoW hacks have been very "light-handed" -- not wanting to dig too deep into the mechanisms. I've seen folks who have installed real servos so they could

*drive* each mechanism to a specific "position"/orientation. But, that wasn't necessary for a speakerphone -- as long as the lips and eyes sort of move coincident with the audio coming from the toy (i.e., your caller's voice!), the effect is good enough. Not sure if that will continue to be my assessment once their roles are changed in the new deployment...

MJE2955 +12 ---+--------- ----------------+--- +9 | e\ /c | | --- --------- | | | | 7809 | | +---[3R]---+---|Vin Vout|---+ | | Gnd | | --- --------- --- --- .33uF | --- .1uF | | | Gnd ---+-------------------+--------+--- Gnd

The above circuit will reduce the 12V (more likely it is

13.8V) from your 5 amp supply to 9V. You'll need a large heatsink, cooled by a muffin fan on the MJE2955 transistor, assuming the toy draws up to 5 amps. The 3 ohm resistor should be rated at at least 1 watt. The 7809 would survive without a heatsink, but would be hot, so use a heatsink there, too.

Ed