Comments by Jan

  • New products: RoboClaw Solo 30A and 60A Motor Controllers

    New products: RoboClaw Solo 30A and 60A Motor Controllers

    - 19 March 2018

    Hi, 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

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 13 March 2018

    Hi, Robert.

    It sounds like you are trying to put your cells in parallel, which can be tricky, to get a 1.2V, 100Ah pack, and then to somehow boost to 12V, which is going to be very difficult and inefficient. You would be better off putting your cells in series, which gets you straight to 12V, and then the only question is whether the D cells can give you 50A. I don't think they can, and you say you saw 30A peak, which sounds plausible to me. So if you really need 50A, you should figure out how to put the two 10-cell packs in parallel (which, again, is tricky, since you're initially shorting two different packs together). If you need a regulated 12V, you could do 20 or more cells in series to get to about 24V, then regulate that down to 12V. I don't know where to get a 50A 12V regulator that can take 40V in, but it will be way more efficient than trying to boost 1.2V to 12V.

    Separately, why don't you just use a 12V gel cell (lead acid) battery? It's pretty easy to get them with about 10-15Ah capacity, which should be able to do 50A peaks pretty easily, and it wouldn't be much bigger or heavier than a NiMH battery.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 26 February 2018

    Hi, David.

    Did you read the main post? It looks like you did not get the point of the amp vs. amp-hour distinction. (Or maybe it's just a typo in what you posted for your battery spec.)

    In any case, if the battery is lasting a week, it's probably good enough. The main problem is that you are trying to use more energy in your lights overnight than you collect during the day. If you want to use 18W for eight hours and you have only 4 hours to collect that, you would need at least 36W. That would be at 100% efficiency, which for sure you will not have, and for the whole time, not just when you get the most direct sunlight. You probably need at least five times your current solar panel capacity.

    - Jan

  • How I picked our new machines (and what they mean for you!)

    How I picked our new machines (and what they mean for you!)

    - 14 February 2018

    Thanks. The bottom-side solder does become liquid again when the board goes through the oven a second time, but the surface tension of the solder keeps the components from falling off. What components we put on the side that goes through twice is something we consider when designing a board since something really heavy could fall off, and some components are better not to put through the oven twice. I don't think the solder joint quality is meaningfully affected by the second reflow cycle.

    - Jan

  • Continuous-rotation servos and multi-turn servos

    Continuous-rotation servos and multi-turn servos

    - 5 February 2018

    Hi, John.

    Either of those routes will probably work, and it doesn't sound very expensive to try. 5k-50k is probably ok for the pot resistance. Let us know how it turns out!

    - Jan

  • New adjustable voltage regulators with multi-turn fine adjustment

    New adjustable voltage regulators with multi-turn fine adjustment

    - 8 January 2018

    Thanks for the feedback. That higher output range you are asking for is not feasible on this particular design. Do you need the 3-16V input range in the same device, or are you wanting the higher output voltage for an application where the input voltage range would be smaller? (I'm asking because it's much easier to make just a step-up converter for low input voltage applications, and the step down/step up (or even straight step down) functionality would be easier to achieve if it did not have to operate at so low of a voltage.)

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 18 December 2017

    Hi, Cindy.

    Your math generally seems right, though the "56 mA per use" is not correct; it's that times the two minutes to get back to units for total capacity. But the 56 mA is probably a more useful figure, as long as you realize it's not "per use" but the average rate over the two minutes. Maybe the motor only runs for 10% of that, and the remaining time the current is negligible, so the peak current draw might be over half an amp but only for ten seconds.

    It sounds like the 5V, 1A adapter will likely be sufficient. In general, it's fine to use a bigger adapter since it's not going to force the currrent into your system.

    - Jan

  • Free shipping, phase two: lots more free shipping

    Free shipping, phase two: lots more free shipping

    - 1 November 2017

    Hi, Dave.

    If you meet us half way, you can get in on the free shipping! Hawaii has other benefits, too.

    I know it's not the same as free shipping, but our international shipping rates are going down, and we keep working on getting them lower. Please also support your local distributors, and maybe bug them for free shipping!

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 18 October 2017

    Hi,

    Your initial calculations seem right, except for the last one being a bit off: for 8 of those D cells I get 17*8*1.5=204; divide that by 4.8 and I get 42.5, not 43.75. Maybe you were approximating that 17 is basically half of 35 since 43.75 is half of the earlier 87.5.

    For the last part, you can be pretty sure about the battery side. If you have 2Ah * 1.2V * 3 = 7.2Wh and you're getting many hours out of it, you can be sure the load is actually less than 3.6W. Maybe that's some conservative upper limit, perhaps at a higher voltage like 4.8V (1.6V per cell), and the actual consumption might be half that at 3.5V and drop even more as the battery voltage goes down. If there isn't some fancy flashing pattern, it should be really easy to just measure the current at different voltages.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 11 October 2017

    Hi.

    For the first question, yeah, your power should basically scale with the number of motors. Keep in mind that you won't necessarily get to use that extra power the way you want to, which brings us to your second question, where the answer totally depends on your system. Even if you have a system in which your output power is constrained to be the exact same in both scenarios, your system efficiencies will not be the same, and more importantly, the motors would not be operating at the same efficiency points. Back to real life systems, if you have more power available, your robot will move faster at top speed or accelerate more quickly, so your output power is unlikely to be constrained to the same value in both situations.

    - Jan

New Products

A-Star 32U4 Prime LV microSD with LCD
12V, 2.4A Step-Down Voltage Regulator D36V28F12
3.3V, 3.6A Step-Down Voltage Regulator D36V28F3
A-Star 32U4 Prime LV microSD (SMT Components Only)
6V, 2.7A Step-Down Voltage Regulator D36V28F6
A-Star 32U4 Prime LV (SMT Components Only)
A-Star 32U4 Prime LV
ACHS-7123 Current Sensor Carrier -30A to +30A
Free Circuit Cellar magazine March 2019
ACHS-7122 Current Sensor Carrier -20A to +20A
Log In
Pololu Robotics & Electronics
Shopping cart
(702) 262-6648
Same-day shipping, worldwide
Menu
Shop Blog Forum Support
My account Comments or questions? About Pololu Contact Ordering information Distributors