Let's Make Robots!

Strange battery behaviour

So i just received the battery i was talking about here

it kind of works, but it has a very strange behaviour: basically when i connect it to a load (just a board, nothing intensive), it just doesn't give energy and the board remains off. If then i connect the other connector to the wall plug, the battery "wakes up" and power the board. Then i can disconnect the battery from the wall and it keeps running for hours.

Has anyone tried this batteries ?

Hi, i found this battery online, they came in different shape and characteristics, from different shoppers in hong kong.

http://www.ebay.it/itm/DC-12V-4800mAh-Super-Rechargeable-Lithium-ion-Battery-/120522025474?pt=UK_ConsumerElectronics_Batteries_SM&hash=item1c0fac2a02

As anyone tried them? they look great for the prize.. Also, no weight is specified, anyone knows ?

 

Android phone as a controller

Hello there :)

I'm on the edge of purchasing an android phone. Looking at specifications around i thought: "Hey but this is the perfect controller for a robot!!" It has an incredible inventory of useful stuff: gps, compass for navigation, wifi, bluetooth and cellular for communication, huge screens for UI, speaker for talking, plenty of cpu, camera, easily programmable, and so on, all packed in a small package, all low power! And all for as less as $200! What do you want more ??

There's only a drawback: there's no simple way to phisically connect a device to peripherals :(

Filtered Linear Power Supply

I was wondering on a site about wireless video transmission, and ended up on this power supply board:

http://www.rangevideo.com/index.php?main_page=product_info&cPath=7_20&products_id=161&zenid=32f8d15754cc1b8054ef3d5a800f706a

Isn't it very very interesting?? 10 bucks and you have a selectable 3.3, 5, 12 output voltage with input between 4 and 35 volts!

Is there something i'm missing or is it very cool?

Servo mounting for "up-down" movement

hello, i was just wondering: which is the best way to attach a servo to a chassis so that it can move an attached camera up and down (no left-right) ?

Live video streaming for remotely operated robots, solutions?

Hello!

I recently tried a small videocamera like this one, and i must say that, despite the low quality, they do a decent job, except when heavily shaked.

Now, the main problem is that they have a limited range, and that they have a radio signal on their own, separated from the main robot control. This means that you cannot make a program that behave based on the images, and that the two radio signals can have different ranges.

PPP over XBee, aka xbee wireless

hello, i was thinking about this stuff: if i have two computer with two xbee connected with an usb connection with a FTDI chip, it should be possible to establish a PPP connection over the (simulated) serial port.

Am i wrong?

with 250 kbps (let's say 20 kB/s ?), reduced power consumes and long range, they could make a good solution.

Ladyada XBee adapter, not so good for Pro modules :(

Hi, just a note to warn you, in the case you're interested in LadyAda XBee adapter for an XBee-pro module.

They're advertized as being compatible but that's not really the case. The PRO modules have a longer tail that goes over the capacitor in the bottom, which prevent placing the module at all.

The guide says: "Make sure the capacitor and regulator sit close to the PCB, especially if you're planning to use an XBee Pro module". Unluckly, that's not enought.

8 volt from 12 volt battery

Hello, i have a wireless camera that wants 8 (or 9) volt input. That's a little weird i think.. Anyway, i have a 12 volt battery, is there a way i can get the 8 volt?

I have a spare 3V regulator and a 5V regulator (the classic L7805 something). Is there a way i can use them together to get the 8 volt?

Schematics appreciated :)

 Thanks!

Small motor controller/driver with variable speed

Hello, i'd like to have some small driver/controller like the L293D or similar, but that can run motors at variable speed. Does it exists ? A small and cheap board would be ok.

If it doesn't, how could it be built ?

 

Thanks :P