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Comments by Jan
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Understanding battery capacity: Ah is not A
- 1 March 2019Hi, Keiran.
No, you cannot trade off the voltage for current in your jack. That 1A rating is going to come from things like how much the contacts or some other parts the current goes through heats up, so if you put 3x more current through, it's going to heat up possibly 9x faster (for a fixed resistance, power goes with current squared). 1A sounds low for a power jack, by the way, so it's possible it's a really cheap unit or they're being really conservative with the rating.
Separately, you should also not connect the AC adapter straight to your battery and expect it to act as a charger. Best case, nothing will happen (i.e. you also won't charge your battery); quite possibly, you'll also break something.
- Jan
Understanding battery capacity: Ah is not A
- 19 February 2019Hi.
The 12V to 5V conversion should get you longer battery life as long as your converter is not really inefficient. With a 100% efficient conversion, you would get 12/5 times that seven hours, or 16.8 hours. Getting at least 85% efficiency should not be too difficult, and that's what you need to multiply your final answer by, so 14 hours should not be too difficult. Getting 15 hours would require 90% efficiency, and that is still pretty realistic.
- Jan
New products: 16-channel QTR MD reflectance sensor arrays
- 31 December 2018Thanks for the feedback! Making a version of these with a microcontroller on board has been on the to-do list for a while, and I hope to get to it next year (I'm writing this on December 31).
- Jan
Electrical characteristics of servos and introduction to the servo control interface
- 27 December 2018Hello.
This is not something to calculate (if you trusted your battery capacity, you could do some calculations based on how long it lasts, but you could only do that for lighter loads since forcing your servo to some max load scenario for a prolonged period would likely destroy it). So, you should just put a current meter in line with your servo and see how much it draws. That would typically show you average current over maybe a tenth of a second or however fast your meter updates. If you want to see the faster peaks, you would need to use an oscilloscope.
- Jan
Continuous-rotation servos and multi-turn servos
- 23 November 2018Hi, Gordon.
I have not heard of such a servo. I don't know if you need the actual feedback and the higher torque you get from typical hobby servos, but perhaps you should look at stepper motors, too (along with our Tic stepper motor controllers: https://www.pololu.com/tic ).
Please share if you do find anything.
- Jan
Servo control interface in detail
- 20 August 2018Peter,
Yes, there is a control board in the servo that takes the signal you send it, compares it to the position feedback on the servo, and drives the motor appropriately. You can look at our Jrk motor controllers to get more of an idea of what could be going on inside the servo:
https://www.pololu.com/product/3142
The Jrk controllers have a lot more interfaces and features than what you would find in typical hobby servos, but the basic idea is the same.
- Jan
Servo control interface in detail
- 14 May 2018Your questions are answered in the rest of the post and other screenshots. When the servo gets the control signal pulse, it sends a pulse of power to the motor based on how big the error is. The energizing of the motor (the current pulse) is not ending because the error went away. You can see in the last screenshot that once the servo is in position with no resistance, there are no current spikes corresponding to the control pulses (the last two).
- Jan
New product: VL53L0X Time-of-Flight Distance Sensor Carrier
- 3 April 2018Hello, Santiago.
Yes, we are planning on that. We have the sensor chip on order, but with the crazy lead times lately, it might still be a few months before we get them.
- Jan
New product: Pololu USB AVR Programmer v2.1
- 23 March 2018Hi, Brian.
Please keep in mind this is just an issue when powering the A-Star from the programmer, so the programmer still works fine if the A-Star has its own power source, which you typically have to have, anyway. But it can be convenient, which is why we improved the feature. There are some tricks you can do, like increasing the capacitance on the programmer side or putting a small resistor in line with the power from the programmer to the A-Star. It's not something we would want to do for a production solution.
In any case, I want your reaction to be, "yay!", not "darn!" when we make better products. If you email us with your order number and reference this comment, we'll send you a couple of the new ones.
- Jan
New products: RoboClaw Solo 30A and 60A Motor Controllers
- 19 March 2018Hi, Jay.
What prices, for which controllers, would you consider not to be "so much"? And if you have some reasons for your prices, please share those as that would also help us give you a better answer.
- Jan