About: A retired electronics engineer -motorola. delveing into new craft ideas and contest entries.

INTRO- Make a string instrument[ example: ukulele] into a violin sound  with a simple small motor in one day.

The device described here is a pick attached to a small battery operated motor and mounted  on a Uku made by Mistic [see- "How to make a mini-Uku,dated 1-14-10"in this Instructable.] The two types of picks  noted here are easily  used on any string instrument.The sound can be similar to a mandolin fast plucking or a violin sound.



Refer to dwg. fig.1 and 2.
Fig.1-Mounted Pick
1-Ukulele or other string instrument. Uku used here was made years ago and described in an Instructable.See Introduction.
2-pick - plastic from old credit card..1 in. long.
3-pick holder plastic vinyl tube .5 in.dia.  x approx long.shoved onto item 4 pulley.
4-motor shaft with a plastic pulley still attached after removal from old DVD player.
5-motor. 1 in. dia. x 1 in. long. A piece of plastic is glued to side to press the tube for speed control with a finger if needed.
6-switch. on-off. found on solar nite lite .Can be any available.
7-screw mounting ass'y. 6-32 machine screw about 1 in. long and 3 nuts.The two top nuts are crammed together as a lock.
8-motor mount swivel.plastic 1x3 in. x .02 thick approx. drill .14 hole for the item 7 screw.
9-bottom mount for item 8 swivel. 1x2 in. aluminum strip  about .010 thick  bent over 1/2 inch and drilled hole for mount.
10-mount screw for  assembly wood screw 6-32  or use silicone RTV glue to side of instrument for easy removal.
11-battery  pack . can be any for 2AA or up to 4 AAcells.{see Radio Shack[ RS}.
12-Variable resistor . 100 to 500 ohms. used to vary speed.Any small potentiometer can be used . Glue to side.
13-Base for assembly- wood. 1/4 x 1/2 in  x 2 in lg. Glued to item 9.
Hand held Pick  from motorized tooth-brush.Brush is type that  vibrates using a 1.5 v.battery. Cost $1.00 .Dollar Store]
wood dowel .40 x 1.00 lg. Cut end for pick. A 6-23 nut is used as counterweight to the weight  on the axle.Glued in place.
Plastic strip- used to vary the rotation and picking operation. Cut off brush and save it for cleaning  operations.
Saw-Pliers. screw driver set. drill and drill bits  .12   and .14 dia. Xacto sharp point for cut slit in tubing.
scissors,tin snips can be used for aluminum. Solder and Iron. 40w. Solder can be 63-37 low melt point.[RS]
E6000 glue .and Silicone glue  RTV type.


Fig.1 Pick-- Assemble as shown.'
Cut a slit in item3.Push a piece of plastic cut out as a pick  into a slit. It holds well.
Force  tube onto axle  item4. if  not esy to do yuo may have to glue it on.
Item 8 can be a plastic strip or aluminum. place motor on end and glue with E6000.Drill a .14 dia hole thru item 8 and 9.swivel  point.
Glue item 6  switch on item 8. Can also be glued any whee else on back of motor mount but must be clear for soldering.

Item 13 glue to under side  of item 9. This piece is a support to hold the motor  and pick tip about 1/8 inch above the strings.
The item 9 strip is flexible so one can force the motor down  for pick contact.

Fig.2 Hand held  toothbrush pick holder.
Cutting operation.-Remove AA battery , Reach in and pull out the motor easily with long nose pliers:. mark a spot about 3.75 in. from end  and use a small saw ,cut off the brush end .Replace the motor and battery.Tesst the end  switch  for good operation.
Place a small weight or a 6-32 nut  on side opposite the weight on end of the axle. Use E6000 glue. dry for 3 hours.
Mount upright and glue the end dowel in place above 6-32 nut counter weight..
Dowel can have a saw cut in end beforehand.This cut is for a plastic pick.about 1 in. long.Use an old credit card for pick.


To play item  Fig.1 motor pick- Mount on instrument .Then turn switch on.
The motor will rotate above the strings about 1/8 inch clearance. Using  slight hand pressure on motor top it will touch the  pick to the strings and cause a strumming action. As in a violin the sting will vibrate at about 100 revolutions /sec. To slow this down you can  do one of two things. 1- push  a finger on the side plastic that is glued to the side of the motor. or  2-adjust the vari-resistor to slow the
motor rotation down  . This can sound like a mandolin  in this case.
Fig 2- Turn the switch on. hold the pick closer to the strings and  to slow the pick  press a finger on the side plastic to the axle.
 that is all  The pick can be held against 2 strings at once also.

Note-To increase the pick action two picks can be mounted on the tube and the frequency of picking will be very high as in a good violin.

Be the First to Share


    • Pocket-Sized Speed Challenge

      Pocket-Sized Speed Challenge
    • Audio Challenge 2020

      Audio Challenge 2020
    • Maps Challenge

      Maps Challenge

    3 Discussions


    8 years ago on Introduction

    I love how simple instrument ideas always can create such nice sounds. Thanks for the instructable, mistic!


    8 years ago on Introduction

    Clever, mistic! This can be used to play guitar, too.


    Reply 8 years ago on Introduction

    hi 2000, I did try it but on the small tooth brush version. Lots of unusual notes !