Wireless battery charging of the body interaction vibrator development board

One major Problem oft DIY electronic sex toys (or massage wands) are the need to charge the batteries. Usually the batteries are charged via the USB connector. This means that there is a physical connection between the sex toy and the USB connector, making it impossible to mold the whole sex toy with eg. silicone.

The solution is to use a wireless charging module (eg. this module from Seeedstudio). It comes in two parts: The sender (IN) and the receiver (OUT). Both are connected with a coil. If you place the two coils close together, the sender coils induces power in the receiver coil. Though you can share the batteries wireless. The receiver could be molded, separating the electronics, batteries, connectors etc. from the environment. The result is a form with a smooth surface enabling secure usage as a sex toy.

We have made an easy DIY solution based on the body interaction vibrator development board, wireless charging module and a 3d printed silicone molding form.

Part A: The molding form consists of two parts.

3d print form A

Step 1: The form comes in 2 parts. Print both parts of the form. The STL file is called part A. After printing polish the inner part of the form as well as the surface between the two sides.

Step 2: Now print out part B. It is used to fasten the board, battery, receiver coil and receiver board.

Step 3: Connect the + pad of the wireless charging receiver board with the pin marked + of the vibrator development board (that’s pin 1 of the MAX1555 battery charging IC). Connect – of the receiver with the GND pad of the vibrator development board. You need two short wires and have to solder them at the two boards.

Step 4: Now wind up the wires connecting the board with the battery and the vibration motor. (The connection to the receiver board is not shown on the image.)

Step 5: Now attach the coil on the shorter “cross” of part B with some glue. There must be space between the coil and the outer longer cross. Then attach the board, battery and vibration motor as shown in the pictures. you can use some glue to fix these parts. Be sure to set the switch to the ON position.

The receiver board can be placed within the coil. It’s the small long board in the middle.

Step 6: Fix part B (with board, coil etc.) at part A. Be sure that there is enough space between them (min. 5mm).

Step 7: Now attach the second part of part A. Use some tinkering wire. Double check: There must be space between Part A and part B. And there must be space between the coil and the upper edge of form A as the coil must be molded by the silicone.

Step 8: Now pour silicone into the form. Use silicone with a high Shore A value. The higher the Shore A value is the higher is the firmness of the silicone form. We have used silicone with Shore A 45. You need about 90 ml silicone.

Step 9: After the silicone gets hard, remove the tinkering wires and softly remove the form A. Remove overhanging part.

Step 10: Now you can remove the outer cross of part B.

That’s it. It takes about half an hour (without printing). Before using check carefully that the silicone is solid. Even if you skew the silicone form you should not be able to feel the edges of the vibrator development board. Otherwise there is the danger to get hurt. Use it as a massage toy on your own risk. For charging the batteries place the molded coil over the sender coil. The yellow charging LED should go on.