Hi all,
I searched and couldn't find a thread on these boards, now common on Aliexpress and eBay and I'm sure plenty of others. Audiophonics has a slightly different version (I think it is a previous revision of the same board but with a different pin out).
Anyway, the principle of operation is that it runs off 5V, uses a microcontroller to switch from one input to another. The lines are switched through 4x 74HC573 D type latches, and each of these is turned on or off via a (momentary, NO) repeated button press via an STC15W101 controller. Upto 8 lines can be switched per input (10 pins) with 2 ground pins. There are different levels on information out there available on these - the Aliexpress info tends to be short, but some ads on eBay contain a bit more info.
I've managed to let the magic smoke out of two of these now, so I can say they aren't super robust, but outside of that do certainly work. On the first one that I killed, I had grounded some of D1-D8, and you'll see in the quoted text below that this is not recommended. In the second case, I believe that I hit a short and some current flowed through the ground. The end effect is that one input stops working in such cases - in essence it becomes a 3 input switch. What I don't know at this point is whether the microcontroller has been killed, or one of the latches. - I will try to figure that out when I get some new parts here.
The text from eBay is quoted here, and you'll see there is reference to the two pinouts.
I've posted this here for comments and any obs anyone might have. I think if there is a way to make this unit more robust, it might be worth it.
I searched and couldn't find a thread on these boards, now common on Aliexpress and eBay and I'm sure plenty of others. Audiophonics has a slightly different version (I think it is a previous revision of the same board but with a different pin out).
Anyway, the principle of operation is that it runs off 5V, uses a microcontroller to switch from one input to another. The lines are switched through 4x 74HC573 D type latches, and each of these is turned on or off via a (momentary, NO) repeated button press via an STC15W101 controller. Upto 8 lines can be switched per input (10 pins) with 2 ground pins. There are different levels on information out there available on these - the Aliexpress info tends to be short, but some ads on eBay contain a bit more info.
I've managed to let the magic smoke out of two of these now, so I can say they aren't super robust, but outside of that do certainly work. On the first one that I killed, I had grounded some of D1-D8, and you'll see in the quoted text below that this is not recommended. In the second case, I believe that I hit a short and some current flowed through the ground. The end effect is that one input stops working in such cases - in essence it becomes a 3 input switch. What I don't know at this point is whether the microcontroller has been killed, or one of the latches. - I will try to figure that out when I get some new parts here.
The text from eBay is quoted here, and you'll see there is reference to the two pinouts.
I've posted this here for comments and any obs anyone might have. I think if there is a way to make this unit more robust, it might be worth it.
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I made another little discovery on these switches - they can be set to switch between 2, 3 or 4 inputs. To do this, close the "but" selector button at power on - doing this repeatedly will cycle through the modes. This had me really puzzled for a while!!
This is why I thought I had damaged the first one (let the magic smoke out comment above) - it turns out I didn't damage it I think, I just had the contacts closed at power up and therefore on power up it went to 3 inputs and so on.
OK, so given that they seem reliable now that I figured that out, it seems that it is not worthwhile trying to reinvent the wheel, especially when these are <10e each.
This is why I thought I had damaged the first one (let the magic smoke out comment above) - it turns out I didn't damage it I think, I just had the contacts closed at power up and therefore on power up it went to 3 inputs and so on.
OK, so given that they seem reliable now that I figured that out, it seems that it is not worthwhile trying to reinvent the wheel, especially when these are <10e each.
Sweet. I just tested this board and it seems to work as described. I just have one question which I don't believe is covered in the (slightly confusing) instructions above... I've configured my board as a 4in to 1out switcher. Can I apply 5v to one of the vacant pins on the output so that whichever input I select, that input would get 5v on it's corresponding pin?
Ex: If I connect 5v to output pin D6, when I select input A, 5v will be sent to pin D6 of input A to power something like a Bluetooth module.
This way the Bluetooth module will only get 5v power while A is selected, then turn off when another input is in use.
Thanks
Ex: If I connect 5v to output pin D6, when I select input A, 5v will be sent to pin D6 of input A to power something like a Bluetooth module.
This way the Bluetooth module will only get 5v power while A is selected, then turn off when another input is in use.
Thanks
The short answer is.... I don't know.
But I imagine that the datasheet for the chip would tell you what current they can handle - probably something quite low like 10-20mA. I also don't know if it will take reverse voltage as I think you are suggesting?
Maybe the thing to do is to use the signal from the controller chip to turn on a transistor that handles the power to the bluetooth module?
But I imagine that the datasheet for the chip would tell you what current they can handle - probably something quite low like 10-20mA. I also don't know if it will take reverse voltage as I think you are suggesting?
Maybe the thing to do is to use the signal from the controller chip to turn on a transistor that handles the power to the bluetooth module?