Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: Half Shell on November 05, 2007, 10:48:04 PM
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So I am working on one project that the motors run at about 5 volts and another where I'll be dealing with 9 volts- since my micro controller runs at 5 volts and I want to make the robots as secure as possible, should I use voltage regulators? If so, how would I use them and what kind would I need?
I appreciate any help given to me.
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Hello ;)
I think this article will help you:
http://www.societyofrobots.com/schematics_powerregulation.shtml
if u dont wanan read it, scroll down to the bottom there's a schematic.
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Wow... I feel silly.
I scanned the site and couldn't find a tutorial on it. Now I feel kinda silly.
Thanks!
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I read through the tutorial and see the diagram - how do I decide what fuse to use?
Also, am I right in saying that I basically need to buy a switching regulator and voltage regulator for every robotics project I do?
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When a fuse is used between the regulator and battery, they protect your battery from short circuiting (lithium batteries can explode), if you are not worried about wasting a battery when you short it for too long, forget about the fuse. You hardly see anybody using one on a small robot using 9V batteries.
If this is for a non-mobile power supply, I'd use a fuse that is rated higher than what I calculate my circuit will need at most.
If I have two motors, I'd estimate about... 4 amps max maybe?
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Also, am I right in saying that I basically need to buy a switching regulator and voltage regulator for every robotics project I do?
You only need a switching regulator if your battery voltage is not at the level you want for your motors or servos (or if your battery voltage is less than 5V). In a typical robotics application you'll probably just want a 5V linear regulator to power your logic; your motors can often just be powered straight off your batteries.
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how do I decide what fuse to use?
http://www.societyofrobots.com/electronics_fuse_tutorial.shtml ;D
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For most small robots, the "standard" 5 volt Regulator of choice is the LM7805... the LM2940 is also a popular one as it is "low voltage drop out". Remember to use filter caps on both the input and output sides along with a heat sink!
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I typically use an LM2940 for size-limited voltage regulators, or where I don't need high efficiency.
Building a switching regulator from scratch is annoying - there are a bunch of hard-to-find parts to deal with, as well as the fact that in order to be a reasonable size, you need to work with surface mount. Lately, I've started using the Dimension Engineering 5 volt switching regulator, and I have to say I really like it:
http://www.dimensionengineering.com/DE-SW050.htm
For $15, its hard to beat, and it will handle 1 amp of output. They also have a 3.3 volt version if you need that voltage. They have another regulator that is really nice - the AnyVolt Micro.
http://www.dimensionengineering.com/AnyVoltMicro.htm
It allows you to feed in almost any voltage (2.6 - 14 volts), and get out any voltage (2.6 - 14 volts). I use this regulator in BrainBot to step up the 9.6 volt battery power to 12 volts for the camera.
- Jon
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Alright, I bought a couple of 1 amp 5 volt regulators and a variable regulator from radioshack, surprisingly not for that much. They should hold me over until I build a much larger more powerful robot.
Plus, with all that I've read and from your kind advice I think I have a handle on how I will be using the regulator.
Out of curiosity, does anyone have a free schematic making program I could use to draw out my robot diagrams ahead of time?
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does anyone have a free schematic making program I could use to draw out my robot diagrams ahead of time?
http://www.societyofrobots.com/electronics_Eagle3D_tutorial.shtml
You keep forgetting to search first :P