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Post by interstar on Jun 5, 2022 15:13:06 GMT
n00b electronics question.
I'm interested in trying to hook up a BBC MicroBit to my AE Modular
I know that although the MicroBit is powered by USB, it works with 3.5 volts and can be burned out with 5.
(At least, I already seem to have killed one MicroBit, trying to hook the output taken from pin 0 to a powered speaker.)
But if I want to continue experiments using MicroBit audio and connect it to AE Modular, what can I do to protect it? Is it enough to put a resistor between that pin 0 and, say, the audio input to a filter or the Master module?
If not, what else can be done?
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Post by keurslagerkurt on Jun 8, 2022 11:41:20 GMT
If it's a high voltage that is the problem, one resistor is probably still a bit risky.
An important question is whether you will only feed the microbit into AE, or do you also want to send sound/cv/.. from AE towards the microbit?
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Post by pt3r on Jun 8, 2022 14:52:37 GMT
The problem you describe here seems to be that your powered speaker required to much amperage output of your microbit thus burning it out.
whereas feeding 5v into a microbit will kill it you could make a voltage divider circuit to bring down the 5v to the voltage required by the microbit.
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Post by interstar on Jun 24, 2022 11:51:06 GMT
If it's a high voltage that is the problem, one resistor is probably still a bit risky. An important question is whether you will only feed the microbit into AE, or do you also want to send sound/cv/.. from AE towards the microbit? Yes. I was initially thinking of sending sound from Microbit to the AE.
You think if I connect the output pin to the audio on the Master module that would probably be OK?
Maybe later it would be nice to get CV in to the Microbit. I could obviously put some kind of voltage divider with a couple of resistors to take the voltage down (as Pt3r suggests)
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Post by interstar on Jun 24, 2022 11:52:42 GMT
The problem you describe here seems to be that your powered speaker required to much amperage output of your microbit thus burning it out. whereas feeding 5v into a microbit will kill it you could make a voltage divider circuit to bring down the 5v to the voltage required by the microbit. That's plausible.
I have no idea how to reason about amperage. I do know how to make a voltage divider with resistors, so presumably I can send safe voltage into the Microbit
But what is it controls the current that, say, the audio pins on the Master module try to pull? I'm very mystified by current demand.
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Post by keurslagerkurt on Jun 24, 2022 12:10:22 GMT
If it's a high voltage that is the problem, one resistor is probably still a bit risky. An important question is whether you will only feed the microbit into AE, or do you also want to send sound/cv/.. from AE towards the microbit? Yes. I was initially thinking of sending sound from Microbit to the AE.
You think if I connect the output pin to the audio on the Master module that would probably be OK?
Maybe later it would be nice to get CV in to the Microbit. I could obviously put some kind of voltage divider with a couple of resistors to take the voltage down (as Pt3r suggests)
That should be 100% safe! If you want to go from AE voltage (0-5V) to a lower voltage, a voltage divider will indeed be perfect and an easy solution. |
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Post by keurslagerkurt on Jun 24, 2022 12:14:13 GMT
The problem you describe here seems to be that your powered speaker required to much amperage output of your microbit thus burning it out. whereas feeding 5v into a microbit will kill it you could make a voltage divider circuit to bring down the 5v to the voltage required by the microbit. That's plausible.
I have no idea how to reason about amperage. I do know how to make a voltage divider with resistors, so presumably I can send safe voltage into the Microbit
But what is it controls the current that, say, the audio pins on the Master module try to pull? I'm very mystified by current demand.
A passive speaker basically acts almost as a resistor (and has as such a certain .. 'Ohms' rating). For example, I had a 10 ohm small speaker, and at the start of my diy adventures I burnt it! Because I hooked it up to something that was almost 9V, and due to ohms law: 9V / 10 Ohm = almost 1A! Which was way too much for the small speaker to handle. Luckily the speaker burnt before my circuit burnt.. For active speakers, I have no clue. Usually they ask close to zero current, as their inputs are buffered (= resistance in range of TerraOhms). And also, there inputs should be around 0V. So I have no clue how that could destroy a microbit.. |
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Post by interstar on Jun 24, 2022 16:08:22 GMT
That's plausible.
I have no idea how to reason about amperage. I do know how to make a voltage divider with resistors, so presumably I can send safe voltage into the Microbit
But what is it controls the current that, say, the audio pins on the Master module try to pull? I'm very mystified by current demand.
A passive speaker basically acts almost as a resistor (and has as such a certain .. 'Ohms' rating). For example, I had a 10 ohm small speaker, and at the start of my diy adventures I burnt it! Because I hooked it up to something that was almost 9V, and due to ohms law: 9V / 10 Ohm = almost 1A! Which was way too much for the small speaker to handle. Luckily the speaker burnt before my circuit burnt.. For active speakers, I have no clue. Usually they ask close to zero current, as their inputs are buffered (= resistance in range of TerraOhms). And also, there inputs should be around 0V. So I have no clue how that could destroy a microbit.. What about the audio for AE? Is that "active" or "passive"? If I were to plug the output of the MB as an audio input to a filter module etc. do you think that would try to draw current? |
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pol
Wiki Editors
Posts: 1,365
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Post by pol on Jun 27, 2022 19:06:56 GMT
A passive speaker basically acts almost as a resistor (and has as such a certain .. 'Ohms' rating). For example, I had a 10 ohm small speaker, and at the start of my diy adventures I burnt it! Because I hooked it up to something that was almost 9V, and due to ohms law: 9V / 10 Ohm = almost 1A! Which was way too much for the small speaker to handle. Luckily the speaker burnt before my circuit burnt.. For active speakers, I have no clue. Usually they ask close to zero current, as their inputs are buffered (= resistance in range of TerraOhms). And also, there inputs should be around 0V. So I have no clue how that could destroy a microbit.. What about the audio for AE? Is that "active" or "passive"? If I were to plug the output of the MB as an audio input to a filter module etc. do you think that would try to draw current? It shouldn't "draw" current, but it will use some of the audio input signal as a natural part of going throught the module's circuitry... That's my understanding anyway! |
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Post by keurslagerkurt on Jun 30, 2022 7:30:35 GMT
Forgot to answer your last question interstarThing with audio inputs of modules is that they are USUALLY active, but you'd have to analyse/get info on each module seperately to be sure. For example, my great divide module is passive, which means it could Hurt your Microbit at it's input side. My other modules use An active input stage, so these would be just fine. So specifically for this reason, it's easiest to use a 'buffer' like the input of the master module or the 4I/O, this basically makes sure the input part is active and protected. |
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