dchang0

Thanks very much for letting me know!I'll double check the schematic and layout to see if I caused the problem with the reset. I might even add a spot to insert a 10k pullup resistor.

Thanks. I'm used to the AtMega48V-10PU's internal pull-up resistors being turned on when I receive them (from Mouser). Let me check the user manual on how to turn them on and off.

I stuck with the original chip that the original designer, Mikey, used to minimize any chance of source code changes or different pin-outs.

FYI, you can now order DIMP 1 or DIMP 2 PCBs through DirtyPCBs.com. Links are provided in the corresponding Instructables. Pricing is roughly the same as through JLCPCB, and you get 10 PCBs per order. You are welcome to sell the spares on ebay where others will likely have saved searches for them.I have also written an Instructable on how to program the ATMEGA48V-10PU in the DIMP 2 using a Raspberry Pi.

Hi, KevinS510--Could you check voltages at these other points?1) Take 9V battery out of the battery clips and measure its voltage. Should be 9.0V or higher.For all the following steps, make sure the black lead on your multimeter is touching a ground point. Pins 4, 6, 8, or 10 on J3 work great.2) Put the battery back in, do not put the chip in the socket yet, turn on the slider switch, and measure the voltage at left end of the diode (the end near the slider switch) with red lead. Should measure 8.7V or higher.3) Then, measure the right leg of the L7805 marked U2. The right leg is near the strain relief holes J5 and J6. It should measure 5.0V or higher.4) Then measure pin 20 on the chip socket again. Make sure you're really measuring pin 20. It's easy to accidentally measure the pin right …

Hi, KevinS510--Could you check voltages at these other points?1) Take 9V battery out of the battery clips and measure its voltage. Should be 9.0V or higher.For all the following steps, make sure the black lead on your multimeter is touching a ground point. Pins 4, 6, 8, or 10 on J3 work great.2) Put the battery back in, do not put the chip in the socket yet, turn on the slider switch, and measure the voltage at left end of the diode (the end near the slider switch) with red lead. Should measure 8.7V or higher.3) Then, measure the right leg of the L7805 marked U2. The right leg is near the strain relief holes J5 and J6. It should measure 5.0V or higher.4) Then measure pin 20 on the chip socket again. Make sure you're really measuring pin 20. It's easy to accidentally measure the pin right next to it. It should measure 5.0V or higher.A failure at any of the above indicates a problem with:1) Dead or low battery. Replace with fresh one.2) Diode probably installed backwards or possibly dead.3) This one could be:a) L7805 installed backwards or is dead.b) Capacitors C4 or C5 installed backwards or are dead.4) Really carefully count the pins and make sure you're measuring pin 20! If you are, and you got the correct voltage in test 3), then there is probably a soldering problem on the chip socket or the right leg of L7805. It's a straight run between those two points, so there isn't much that can go wrong.Let me know how it goes.

PCB and pre-programmed ATMEGA48V-10PU are now up on ebay. See the link in step 1.

Here's another example of a real-world use. A friend of mine moved across the country. He had a car shipping company ship his off-roading truck. When he got his truck back, some of the contents had been removed and other contents were not his. It looked like the shipper had driven his truck into the woods and had a camp-out, because they left camping supplies.If he had had a GPS tracker in his vehicle running under the dash, he could have shown the owner of the shipping firm the proof that one of the employees had taken his truck for a spin.

Randy:The switch for the 9V battery is an ALPS SSSU012200.You can buy them from Avnet for 24 cents each.https://www.avnet.com/shop/us/products/alps-alpine...To replace it you would need to desolder the old switch with a pencil soldering iron and desoldering wick/braid OR a desoldering suction bulb.

For Step 11, it's a good idea to add hot glue or epoxy to glue down the AC port. It snaps through the board, but I found that mine would lift up when pushing the AC cord into the port.