Conception de 2 circuits imprimés avec capteurs à effet hall , et une carte arduino , pour un accordéon


Hello peter, I returned from holydays, I resume my project. I have 2 questions?
I have very long (15 meters) of internet cable that are 8 strands 26AWG, I think it would be good for my assembly inside the accordion with pins dupont 7 pin and 10 pin, that do you think?
Another question, the 7 pins and 10 pins housing exist only for female pins, or also for male pins?
This afternoon I finished my bindings in aluminum and I edit the two circuit boards. See you soon philippe
thank you for your reply


As long as it is flexible enough to fit it should be fine.

The headers will take either male or female pins so you can make either gender with the same header or mixed (although there normally isn’t a reason to do that).



Good evening, Peter

Thank you for your reponse, yerterday, I could not work on my project. Tomorrow I will have little time to advance on the second sketch. Normally there is no gap. I ordered the clamp, the pins and the connectors for the dupont wires and pins. Next week it should be calmer to finalize the project. Good day philippe


hello peter,
I positioned the two fasteners and made the holes at the ends for the printed circuit of the left hand. I reduced the board to 331 mm because I have many mechanical obstacles, stems of the registrations, … It is more prudent not to pierce the circuit at the ends, I will then realize at the reception with a paper matrix that I made on which I spotted my 2 holes. I made you some pictures (3). Tomorrow I look at the right hand I fix my two legs in aluminum, I realize my matrix paper and I recontrôle my sketch. But normally it should be good except maybe the total length after adjustment on the final fixings. Thanks for your help .

What do you think ?

accordion-left-hand-Sketch (5) (1).fzz (177.5 KB)


The mechanical fitting is often the most difficult part of a project like this. It is easy for either you or I to adjust the size and placement of the mounting holes and sensors while it is still just a Fritzing sketch. Changing produced boards is more difficult, so I agree careful consideration now is valuable and trying it out with perf board to make sure the images will work in real life is also an excellent idea. It looks like things are going well.



T I will test the two circuits in real condition with my arduino card with Dupont connectivities of 20 cm and a sound module before installing it in my accordion. Question :Can we make oval holes to have some play for editing?


Hello Peter I made the fixations for the right hand he will have to pay attention to position the circuit board because the rods are not at the same height and therefore the sensors will be difficult to tilt to be in front of the magnet to the good distance. the sensors will face the round keys that you see in the photo


Unfortunately no Fritzing doesn’t support anything but round holes.



Hello peter, I saw again the circuit of the right hand he make 333mm long and I positioned several holes (3) at each end. I must be able to choose the location because I can not exactly define the exact location with my problem of stems at different levels! The contact will be made (note on note off) about 9 mm between the magnet and the sensor receiving head. I must be able to lower the sensors enough but they are very short! It’s really very complicated and almost insurmountable for the right hand! For the left hand I have no problem of this kind everything is at the same level. Good brief I advance but very slowly. It’s a real headache! as we say in French! I will try tomorrow to position the holes for the left hand.
question: I will have enough room for fixed all the wires (34) that will leave each circuit board? …at the next episode! philippe

accordion-right-hand-Sketch (2) (1).fzz (186.1 KB)


Hello again,
I put the holes for the left hand! . For the two sketches of the printed circuits they are aligned normally (right / left) on three levels to be able to fix the card on one of the three levels. Can you check the accuracy of my details
thank you

accordion-left-hand-Sketch (5) (1) (2).fzz (177.2 KB)


6 of the wires are common, so you can connect 3 to the left (31 wires) and the other three to the right (31 wires) to reduce the number of wires in each hole. If 31 wires won’t fit through the hole you have, you may be able to find wire with thinner insulation that will fit. As I said the mechanical side of this is at least as hard as the electronics, and less familiar to most electronics folks. The holes in the sketches look fine (I can’t comment on position, though). You can use inspector to get where Fritzing thinks the holes are or you could try the tool described here which (with some work and the installation of java) can find positions in a drawing for just this purpose:

There are two errors in the right hand sketch. U21 has a short from ground to the output pin, and U7 has a short between power and ground. Both were likely caused by moving the mouse over the pins with a click which creates a wire (it is distressingly easy to do in Fritzing :slight_smile: ). I could tell because schematic at the bottom said there were two nets to route rather than the correct routing complete. I have deleted the two stray wires in this sketch.

accordion-right-hand-Sketch (2) (2).fzz (185.5 KB)



Peter I think there is less wire per circuit board either 9 + 6 + gnd + 5 volt +6 common (6: 2) or 17 + 6 common = 23 wires per circuit board. my question is more to keep the wires on the circuit board?
I do not understand why there are two rows of connectors of 17 pins (j1 and j 2 )I thought that there are interconnected! One row would be used in full, the other one would connect only 6 common wires this is that ?


You are correct it should be 20 wires per board. 9 + 6 common + 5V + gnd + 3 common wires to the mega on each board. The two connectors are indeed connected together to give you somewhere to connect the common wires between the two boards and the mega. If you don’t need the bypass cap (or chose not to install it) you can reduce that to 19 wires per board by not connecting the ground to either board.



hello peter

Here I have I think finalized the 2 circuit boards, I remain perplexed on the final assembly with the right hand because it will probably adjust the sensors with extensions but it’s hard to say! I will receive my material soon. What do you think for the command of the two circuits, it is ok ?accordion-left-hand-Sketch (5) (1) (2).fzz (178.3 KB)
accordion-right-hand-Sketch (2) (2).fzz (185.8 KB)


Looks good, except the left hand sketch again has a power/ground short on U49 this time. Corrected in this sketch.

accordion-left-hand-Sketch (5) (1) (4).fzz (177.3 KB)



Hello peter, here are the two circuits completed. I made the holes of the ends at 3.2 mm. I can order the circuit boards at Asler at 51 € for each hand is 102 €. what do you think ?accordion-left-hand-Sketch (5) (1) (4) (2).fzz (178.1 KB)
accordion-right-hand-Sketch (2) (2).fzz (185.8 KB)


I had a look at the gerber output and don’t see anything obviously wrong, so I think you should be good to order boards.



hello peter; I always test this system of connectivity on my arduino card with connectors prepared. It’s not terrible, it takes room in height and it does not fit very well. I think I will solder my wires directly to the red pines and put a heat-shrink sleeve on each pin. I really prefer the nappes and connectiques for computer . I have not ordered the 2 circuit boards yet.


That is certainly the best solution as many failures are from connectors that don’t connect properly especially with vibration and motion (which are present here). The downside is having to unsolder to replace broken connections, but I suspect soldering on all connections will be the most reliable solution.



Hello peter I ordered my 2 circuits at Asler and
I will receive longues pin headers, I can solder the wires on pins headers with a heat shrinkable sheath.

I will tell you about my second project "to make a circuit board for an accordina.
thanks for your collaboration. philippe