I have a query about the reset protection circuit capacitor. On the PCB and in some circuit diagrams in the PDF it's described as a 35V 470uF electrolytic, but in the section about the reset protection circuit it's described as a 47uF electrolytic.
Which is correct? (The 35V 470uF is physically huge and won't fit without being extended off the board!) Does it need to be bipolar or will a normal electrolytic do? And does it need to be rated at 35V given the supply voltage is 12V and the Arduino circuitry runs at 5V?
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Hi Adrian
bipolar=electrolytic
I grew up calling them electrolytic, and even when I taught electronics to students way backl I referred to them as electrolytic, but nowadays they are called bipolar.
either 47uf or 470uf is fine. Obviously one has a greater RC time constant and thus will take longer to charge when power is applied, but either is fine. I had used 47uf till I ran out of them then started using 470uF because I had a packet of those lying around doing nothing at the time.
35V preferred, but you could use a lower 16V. I don't like to under-rate these and generally go with
2-3x supply rail. But that is a personal preference. There are smaller 35v around, they are taller, but have a smaller diameter.
Cheers
Robert
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Thanks Robert. I hadn't heard them called that before so I was wondering if it was one of the fancy ones that can take voltage in either direction. Since it doesn't sound too critical I've just used a 25V 100uF same as the other electrolytic. (Tbh I'm only fitting it for completeness as it sounds like the reset prevention is only required with ASCOM, and I'll be using it with INDI...) The final part I need to make the power cable should arrive tomorrow and I'll be able to start testing and calibrating it.
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The purpose is to prevent the nano chip resetting when an app connects to it - that is the default behaviour requardless of OS type.
Which can cause problems in both Windows and Linux - If the chip takes too long in resetting then the app can think there is nothing connected and timeout.
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I have a query about the reset protection circuit capacitor. On the PCB and in some circuit diagrams in the PDF it's described as a 35V 470uF electrolytic, but in the section about the reset protection circuit it's described as a 47uF electrolytic.
Which is correct? (The 35V 470uF is physically huge and won't fit without being extended off the board!) Does it need to be bipolar or will a normal electrolytic do? And does it need to be rated at 35V given the supply voltage is 12V and the Arduino circuitry runs at 5V?
Hi Adrian
bipolar=electrolytic
I grew up calling them electrolytic, and even when I taught electronics to students way backl I referred to them as electrolytic, but nowadays they are called bipolar.
either 47uf or 470uf is fine. Obviously one has a greater RC time constant and thus will take longer to charge when power is applied, but either is fine. I had used 47uf till I ran out of them then started using 470uF because I had a packet of those lying around doing nothing at the time.
35V preferred, but you could use a lower 16V. I don't like to under-rate these and generally go with
2-3x supply rail. But that is a personal preference. There are smaller 35v around, they are taller, but have a smaller diameter.
Cheers
Robert
Thanks Robert. I hadn't heard them called that before so I was wondering if it was one of the fancy ones that can take voltage in either direction. Since it doesn't sound too critical I've just used a 25V 100uF same as the other electrolytic. (Tbh I'm only fitting it for completeness as it sounds like the reset prevention is only required with ASCOM, and I'll be using it with INDI...) The final part I need to make the power cable should arrive tomorrow and I'll be able to start testing and calibrating it.
The purpose is to prevent the nano chip resetting when an app connects to it - that is the default behaviour requardless of OS type.
Which can cause problems in both Windows and Linux - If the chip takes too long in resetting then the app can think there is nothing connected and timeout.