Step 6: Original Design Using 555 Timer
Some drawbacks in using the timer circuit are:� you have to use a 4 cell battery pack.� It won't run on any less voltage.� This will ensure that the servo will run very quickly, sometimes too fast in my opinion.� Using a modified servo, you can use 3 or possibly even only 2 cells, making the machine run at a slower, more spookier speed.�
Another drawback of using the 555 timer version is placement of the mechanical parts are limited due to a standard servo only having 180 degrees of rotation.� Using a modded servo or gearbox/motor will allow easier design and placement of the parts.
The only advantage with using a standard servo and the circuit is that just about any servo can be used, and if it should break or wear out, replacement is simple.
But when pondering the concept of the Useless Machine, perhaps going with the most complicated version is the aesthetically superior choice. � �
Note:� if you need more rotation from the servo, change R3 to 10K.
sirus20x6 edited the 2nd schematic putting the pins in order.
colin55 provided the 3rd version.
All of the schematics are basically the same circuit, just arranged differently.