6 volts for the BOE-Bot from a 12 volt battery?
L. Scott Hudson
Posts: 11
I have not received my BOE-Bot and it has been three weeks since I won the auction... curses E-Bay!!· But one day before the deadline to get my money back the guy writes back and says he shipped it and I should receive it this week.· So I'm still pretty clueless about programming it, or how the motors or electronics work, or electronics in general.
This is what I want to do:
http://miayawear.com/gala_dolly.jpg
I removed the 12v gearboxes and 12v battery from a Little Tikes Hummer H2.· I want to convert the 12v battery current to 6v.· Is there a simple way to do this without buying expensive parts? Cheap parts are okay, or cannibalized parts from a VCR or CD player (I have quite a few dead ones).·
1) Can I convert the 12v battery current to a 6v current, and then replace the BOE-Bot power supply with the 12v converted to 6v battery current, and How?··or will it blow up the BOE-Bot?
2) If (1), then can I use the 6v current to power the motors? I have replaced the H2 12" wheels with 8" lawn mower wheels, and it still goes too fast. If I reduce the voltage, does it make the gearboxes go slower, or does it make them less powerful? I have no idea.
3) Can I simply replace the BOE-Bot continuous rotation servos with the motors, or is there more involved?· A local robotics professor said that I need a motor controller.· I don't want to use a motor controller; I want to do it electronically.
Can someone provide me with a really simple step-action process to get what I want?
Thanks!
L
This is what I want to do:
http://miayawear.com/gala_dolly.jpg
I removed the 12v gearboxes and 12v battery from a Little Tikes Hummer H2.· I want to convert the 12v battery current to 6v.· Is there a simple way to do this without buying expensive parts? Cheap parts are okay, or cannibalized parts from a VCR or CD player (I have quite a few dead ones).·
1) Can I convert the 12v battery current to a 6v current, and then replace the BOE-Bot power supply with the 12v converted to 6v battery current, and How?··or will it blow up the BOE-Bot?
2) If (1), then can I use the 6v current to power the motors? I have replaced the H2 12" wheels with 8" lawn mower wheels, and it still goes too fast. If I reduce the voltage, does it make the gearboxes go slower, or does it make them less powerful? I have no idea.
3) Can I simply replace the BOE-Bot continuous rotation servos with the motors, or is there more involved?· A local robotics professor said that I need a motor controller.· I don't want to use a motor controller; I want to do it electronically.
Can someone provide me with a really simple step-action process to get what I want?
Thanks!
L
Comments
Any EEs in this forum?
A "motor controller" IS how you do it "electronically".
Yes, if you drop the voltage on a 12 volt motor from 12 volts to 6 volts, you drop both the speed and the power.
The way you control speed (and power) on a DC motor is with something called "Pulse Width Modulation" or PWM. What this means is, instead of holding the power at 12 volts (or 6 volts) you 'pulse' the power. "Motor controller" circuits like the HP-25 sold by Parallax are very good at doing this. Processor circuits like the BS2 are bad at it. Thus the recommendation to add a "Motor Controller" to your project.
Bottom line -- if you want help and advice, select a FEW issues, get a FEW answers, THEN ask the next question. If you try to get all your issues resolved in one post, you wind up with a confusing post few people will want to answer. And you'll get confusing answers.
1) The Wikipedia is your friend. There are lots of good explanations of concepts, complete with examples and references. For example, do a Google search for "wiki motor controller" and see what you get. Rather than saying "I don't want to use a motor controller", look it up and learn what a motor controller does and what the functional pieces are and which ones you need regardless of how you do the rest.
2) Parallax has scads of excellent tutorials ... all downloadable for free. They explain all sorts of things relevant to robots. Check them out.
3) Parallax also has a series of columns in its archives called Nuts and Volts ... all downloadable and containing explanations and examples and ideas that can be used in robotics and other control applications. Check them out.
4) There are other useful websites. Particularly www.emesystems.com.
5) The idea is to look at what's available so, in addition to getting immediate information, you have some notion of what's available, so, when you have a question, you know where to look ... "Hmmm, I know there was something I saw about this once upon a time ...".
It is many issues to an EE, but to an English Major like myself, there is only one issue and that is getting the friggin Boe-Bot attached to the Little Tikes Hummer H2.
Also the cost of a Motor Controller seems pretty exhorbitant. Someone told me it was like $120. I was hoping there would be something as simple as unplug the continuous rotation servos from the Boe-Bot, and plug in the motors to where the servos were plugged in, and do the rest programmatically.
Would it be easier to dump the 12v Hummer H2 and get a 6v Power Wheels? I've seen them on Craigslist for $25-$35.
Also, I am still waiting for my Boe Bot -- the guy must have shipped it snail mail using actual snails -- so a lot of this is just hypothetical anyway, but you guys have been helpful.
L