robin_1456

planning on buying an SBrick but need help.

Recommended Posts

hi all. i recently decided on buying an SBrick to compliment my 12 existing lego PF motors. but.... i was exploring their website to find out more about the SBrick, and went to the (support hub) section, clicked on the SBrick and scrolled down to (technical info) and it gave me this information 

  • Casing material: ABS (acrylonitrile butadiene styrene)
  • Operating temperature range: -20°C – 60°C
  • Operating voltage range: 3V – 5.5V
  • Maximum continuous current total: 500mA
  • Maximum continuous current per channel: 500mA
  • Range: up to 50 meters. It depends on the controlling device, the SBrick’s distance from, and the electrical properties of the ground, and the orientation of the unit. Deep “null” areas might exist closer to the SBrick than the maximum range.

what i dont understand is how can the operating voltage range be 3-5.5 volts if you're supposed to power the SBrick with a PF battery box (they suggest this), that contains 9 volts? so im worried that if i buy an SBrick that its not going to have enough output power, compared to the IR receiver i use.

so my questions are

1: can someone who has bought an SBrick in the last 1-2 years, please tell me what the output voltage is when powered by a PF battery box containing 9 volts?

2: would u still recommend buying an SBrick?

3: and is this information above, correct?

Edited by robin_1456

Share this post


Link to post
Share on other sites

Well, I checked out their website (busy buys busy I must say, it is - to the extent of being ... modern)

What I believe to have read was this: "Recommended operating voltage range: 4V – 10.8V"

So my answer to your question 1) would be: No clue, where the 3 - 5.5V range came in. This must be the internal power rail distribution to the chippies. You hook up a power supply at the bottom of the brick. When using a 9V battery box, 9 (minus maybe a little) volts are present at the outputs, when doing 100% PWM. When supplying 4V, there are 4V at the outputs (100% PWM). The logic circuits (brains) can still handle this, as they may have an internally stabilized 3.3V voltage regulator. The outputs (drivers) are just channeling input voltage to the motors/actuators. More or less. This is what I am reading.

2) No idea.

3) The 3 - 5.5 V operating voltage range is ... highly questionable :pir-wink:, and as they say: It is 4 - 10.8V. (Not 11! Or even 12V. Sigh.) The amperage sounds OK. ABS - sure, nice material, China knows how to mold that for sure. Temperature, yeah sort of - however, when you run the SBrick at 60°C ambient temperature (to be expected rather sooner than later, after this conference they had), I bet it will rapidly fry when rotating some XL motors under load - well it won't fry, it will simply shut down. Then you need to cool it off - and then you can go nuts again! What else? Range ... 50 m. Yes, possible. I believe it uses BLE - so any experience with modern headphones and so on apply here as well: One solid concrete wall and 50 m becomes 5 m or even less.

Best,
Thorsten

Edited by Toastie

Share this post


Link to post
Share on other sites
13 hours ago, Toastie said:

Well, I checked out their website (busy buys busy I must say, it is - to the extent of being ... modern)

What I believe to have read was this: "Recommended operating voltage range: 4V – 10.8V"

So my answer to your question 1) would be: No clue, where the 3 - 5.5V range came in. This must be the internal power rail distribution to the chippies. You hook up a power supply at the bottom of the brick. When using a 9V battery box, 9 (minus maybe a little) volts are present at the outputs, when doing 100% PWM. When supplying 4V, there are 4V at the outputs (100% PWM). The logic circuits (brains) can still handle this, as they may have an internally stabilized 3.3V voltage regulator. The outputs (drivers) are just channeling input voltage to the motors/actuators. More or less. This is what I am reading.

2) No idea.

3) The 3 - 5.5 V operating voltage range is ... highly questionable :pir-wink:, and as they say: It is 4 - 10.8V. (Not 11! Or even 12V. Sigh.) The amperage sounds OK. ABS - sure, nice material, China knows how to mold that for sure. Temperature, yeah sort of - however, when you run the SBrick at 60°C ambient temperature (to be expected rather sooner than later, after this conference they had), I bet it will rapidly fry when rotating some XL motors under load - well it won't fry, it will simply shut down. Then you need to cool it off - and then you can go nuts again! What else? Range ... 50 m. Yes, possible. I believe it uses BLE - so any experience with modern headphones and so on apply here as well: One solid concrete wall and 50 m becomes 5 m or even less.

Best,
Thorsten

thank u for putting your time and effort into my question it means a lot. 

so my question is (if u dont mind) you said that (the amperage sounds ok) so 500mA right? but i thought 1 volt = 1000mA so a battery box with 9 volts should have 9000mA? so 500mA will be underpowered? 

please correct me if i am wrong 

 

Share this post


Link to post
Share on other sites
1 hour ago, robin_1456 said:

thank u for putting your time and effort into my question it means a lot.

You are very welcome, glad to be of help - provided it helps at all.

1 hour ago, robin_1456 said:

but i thought 1 volt = 1000mA

Unfortunately, this is not correct; the equation would be equivalent to 1 German apple = 1000 milliliters of Irish whiskey :pir-laugh:

OK, so here we go: Volt (V) is the electric potential difference between two electrodes, in this case between the two terminals of the battery box. 6 x 1.5V fresh batteries in series (this is what the battery box does for you, when you put the batteries in: It puts them into series) will lead to a voltage of about 9V.

Ampere (A) is the current that flows from one electrode (battery terminal) to the other, which will only happen, when the two have a potential difference = voltage between them and "something" is electrically connecting the two terminals.

So 9V has nothing to do with milliamperes - the latter will only "flow", when you bring the two electrodes into contact with an electrical resistance (R) - and this can be a motor, a lamp, anything that conducts electricity. The current flowing between two electrodes at different potential depends on a) how big is this difference (= voltage), b) how big is the resistance (R), and c) how much current (= Amperes) can the source (the batteries) deliver?

With fresh alkaline batteries, the maximum current that they can deliver is always larger than any of the LEGO motors/lights can "draw". However, in case of an SBrick, this one sits between motor and battery box, and you control the maximum amount of current flowing in this circuit [battery box (+) terminal -> SBrick in -> SBrick out -> motor in -> motor out, -> battery box (-) terminal]. In principle that is - in reality it is a bit more complex. But that does not matter here.

Now returning to the SBrick website, I find:

  • Recommended max. continuous current/channel: 1A
  • Absolute max. continuous current/channel: 2A
  • Absolute max. peak current/channel: 3A
  • Absolute max. continuous current intake from „0“ and „9V“ pins: 3A

So this is quite different from what you found. The SBrick has 4 channels. PF motors usually do not "draw" more than 1 A (1000 mA) of current (here is a very good reference: https://www.philohome.com/motors/motorcomp.htm). So with 4 motors hooked up to the SBrick, even with all under some load, you should be good - the limit then becomes the supply line from the battery box: The SBrick can only suck in 3A from the source, even when you have one that can deliver more than 3A. This also means that you cannot have all four outputs at max. continuous current (2A each = 8A total) as the SBrick does not allow you to draw such a current from the source, it maxes out at 3A. Or the other way around: 1 motor at full maximum current (3A) maxes out the SBrick (3A) - 4 motors at 0.5 A = 2 A are fine.

Hope that makes any sense ...

Best
Thorsten

 

Edited by Toastie

Share this post


Link to post
Share on other sites
2 hours ago, Toastie said:

You are very welcome, glad to be of help - provided it helps at all.

Unfortunately, this is not correct; the equation would be equivalent to 1 German apple = 1000 milliliters of Irish whiskey :pir-laugh:

OK, so here we go: Volt (V) is the electric potential difference between two electrodes, in this case between the two terminals of the battery box. 6 x 1.5V fresh batteries in series (this is what the battery box does for you, when you put the batteries in: It puts them into series) will lead to a voltage of about 9V.

Ampere (A) is the current that flows from one electrode (battery terminal) to the other, which will only happen, when the two have a potential difference = voltage between them and "something" is electrically connecting the two terminals.

So 9V has nothing to do with milliamperes - the latter will only "flow", when you bring the two electrodes into contact with an electrical resistance (R) - and this can be a motor, a lamp, anything that conducts electricity. The current flowing between two electrodes at different potential depends on a) how big is this difference (= voltage), b) how big is the resistance (R), and c) how much current (= Amperes) can the source (the batteries) deliver?

With fresh alkaline batteries, the maximum current that they can deliver is always larger than any of the LEGO motors/lights can "draw". However, in case of an SBrick, this one sits between motor and battery box, and you control the maximum amount of current flowing in this circuit [battery box (+) terminal -> SBrick in -> SBrick out -> motor in -> motor out, -> battery box (-) terminal]. In principle that is - in reality it is a bit more complex. But that does not matter here.

Now returning to the SBrick website, I find:

  • Recommended max. continuous current/channel: 1A
  • Absolute max. continuous current/channel: 2A
  • Absolute max. peak current/channel: 3A
  • Absolute max. continuous current intake from „0“ and „9V“ pins: 3A

So this is quite different from what you found. The SBrick has 4 channels. PF motors usually do not "draw" more than 1 A (1000 mA) of current (here is a very good reference: https://www.philohome.com/motors/motorcomp.htm). So with 4 motors hooked up to the SBrick, even with all under some load, you should be good - the limit then becomes the supply line from the battery box: The SBrick can only suck in 3A from the source, even when you have one that can deliver more than 3A. This also means that you cannot have all four outputs at max. continuous current (2A each = 8A total) as the SBrick does not allow you to draw such a current from the source, it maxes out at 3A. Or the other way around: 1 motor at full maximum current (3A) maxes out the SBrick (3A) - 4 motors at 0.5 A = 2 A are fine.

Hope that makes any sense ...

Best
Thorsten

 

ok wow, thank you agen for putting so much time and effort into my question. this has been such a big help me. i got the 1 volt = 1000mA from a searching (convert volts to mA) not really sure what happened there. and thanks for the website link. 

most of this makes sense to me by the way 

Share this post


Link to post
Share on other sites
16 hours ago, robin_1456 said:

i got the 1 volt = 1000mA from a searching (convert volts to mA) not really sure what happened there.

It is true, but only in one specific case - for a 1 Ohm resistor (or part of a circuit with 1 Ohm resistance). It's Ohm's law. Voltage = current x resistance.

Share this post


Link to post
Share on other sites
39 minutes ago, MAB said:

It is true

Well, no :D

It's the equal sign that makes it wrong, as in chemistry, physics and when ever an "amount of something" is dealt with, that amount is described by a number and a unit. Your equation is of course correct, U [V] = R [Ω]·I [A]; in other words, 1 V = 1000 mΩ·A and all is good :pir-laugh:

Spoiler

Sorry for being that nerdy - but as I make my money partly with teaching physical chemistry, I per definition need to be that nerdy - in chemistry it is even getting worse, as the mole is not representing a rodent but an awful lot of atoms or molecules. So when an answer is: 1 g H2O = 1/18th mole of H2O, it is wrong, both the "of" and the "=" are wrong; 1/18th mole of H2O is 1/18th of 6E23 H2O molecules, which happen to weigh 1 g at standard conditions. And then we have the molar mass M - and some people call that Mol. 1/18th of 1 M(ol) of H2O is 1 g ...

Oh well. Yes, they don't like PChem. Well I did not like it back then - which changed over time :D :pir-wink: 

Best,
Thorsten

 

Share this post


Link to post
Share on other sites
8 hours ago, MAB said:

It is true, but only in one specific case - for a 1 Ohm resistor (or part of a circuit with 1 Ohm resistance). It's Ohm's law. Voltage = current x resistance.

thanks

7 hours ago, Toastie said:

Sorry for being that nerdy

no worries, im just grateful that you were so help full. thank you

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.