JonMackey

You're welcome.

Nope, no risk at all. I thought about that too. The most it can pass through to the 3v3 regulator is 12V and that is within its rating. You just don't want the motor attached before you adjust it.

Is this an academic question or are you seriously considering developing something yourself? Yes this circuit could be adapted for an LED/photodiode by removing the DC-DC module, flyback diode, and motor control MOSFET, adding a few jumpers and an extra wire to the drum. I wouldn’t recommend it though, dust clings to everything on the inside regardless of when you start monitoring (even if it’s well grounded.) One addition I am considering is adding a digital magnehelic to determine when the filter is overloaded (and send a different audio alert to my hearing protector.) When using a wide belt sander the filter loads way before the drum is full. I figure it it could be built using an inexpensive digital barometer module.

Yes, the interface powers the caliper. By design you should not install the caliper battery when using the interface otherwise you can't zero the caliper programmatically.

I'm glad you liked the design.I just added a new version of the board. In this latest version I added a usb serial interface, resettable poly fuses and LED function indicators below the function selection buttons.

Glad you liked it. I've been through the process of installing spiral pipe twice. Once when I was living in Massachusetts, and again here in New Hampshire. I was able to reuse about 90% of the pipe and fittings.

Let me know if there's anything specific you would like me to clarify.If you'd rather not discuss this publicly, send me a message.

jon@mackey.com

Happy New Year to you!As you were confused about the purpose of my Varmint Detector instructable, I was equally confused about the point of yours. I think some of the confusion is due to the translation to English. The first two times I looked at your project I didn’t make it past the first few paragraphs (like you with mine, I just lost interest.) I kept coming back to it because I’ve designed several boards that use the ATtiny84A and 85.Things I found confusing:- why you would use an ATtiny84A if you needed so many I/O pins? Why not use a different mcu such as the common ATmega328p? An ATmega328p doesn’t cost much more and if you really didn’t care about timing accuracy you could even use the internal resonator and eliminate the need for an external crystal.- how do you download ...

Happy New Year to you!As you were confused about the purpose of my Varmint Detector instructable, I was equally confused about the point of yours. I think some of the confusion is due to the translation to English. The first two times I looked at your project I didn’t make it past the first few paragraphs (like you with mine, I just lost interest.) I kept coming back to it because I’ve designed several boards that use the ATtiny84A and 85.Things I found confusing:- why you would use an ATtiny84A if you needed so many I/O pins? Why not use a different mcu such as the common ATmega328p? An ATmega328p doesn’t cost much more and if you really didn’t care about timing accuracy you could even use the internal resonator and eliminate the need for an external crystal.- how do you download code onto your board? I didn’t see something that looked like an ICSP connector.- why use an 74HC595 when you’re essentially implementing a bus expander? (or is that your point?) A bus expander such as the common I2C controlled PCF7584 would be easy to add, only taking two pins on the ATtiny. You can hang several of these off of the I2C bus and they even make a 16bit version which is handy for creating keypads. Both versions have an interrupt line so the ATtiny doesn’t have to poll to see if something has changed. (and they make DIP versions of these chips too)- I also noticed that you don’t consistently use decoupling capacitors. Is that because the PCB traces you use are so wide you don’t need them? I really like the ATtiny84A though. If you have never played with sleep and the other interrupts you should check them out. They’re quite useful for battery powered devices. For example I use pin change interrupts to implement the remote control for the Varmint Detector. The ATtiny only wakes up when someone presses a button. You can debounce the buttons in software pretty easily, no extra hardware needed (you don’t even need pull up resistors.)Off topic: How did you print the cover of your project?, it looks really professional.

I added a one line description of what this project is close to the top of the description. This is in the "Technology" category, so I left in the details in the description of what chips were used and most of how the detector reacts to motion.If you feel I still need to pare it down more, you'll need to give me some pointers.You have a happy 2019 too.