Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com has links to 45,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.

HOME Schematics Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches
Welcome to DiscoverCircuits.com - online since 2002

See Media Kit for
Advertising Opportunities

Attention Designers:  Please alert us by eMail if we have linked to sites
where your original material has been copied without your permission.
We will change to the LINK to your site.  
Thank you.


Circuits designed by David Johnson, P.E.
Last Updated on: Wednesday, October 18, 2017 05:04 AM

List of Dave's Circuit Designs

The contents & graphics of Discovercircuits.com are copyright protected.
LINKING to Dave's circuits is permitted but DO NOT COPY any files to your WEB SITE server

More details found in DC Magazine

Coin Operated Telescope
designed by David A. Johnson, P.E.

My client owns several coin operated telescopes.  Their problem is that the battery needs to be replaced every few months. I needed to design a new circuit to control the shutter.  The solenoid used was too power-hungry.

Once the coin was accepted and fell into the coin box, a motor would open the shutter for 2 minutes.  After those minutes had elapsed, the motor would reverse direction and close the shutter.  The timer would allow only one coin at a time.   

The circuit that controls the electronic timing sequence is fairly simple.  I designed the control system using some standard logic devices.  The coin acceptance mechanism provides a switch closure when a quarter fell into the coin box.  This starts a timer.  Power is routed to the flapper motor.  When the flapper was fully open, a motor stall current sensor turns off power to the motor.  This leaves the shutter in the fully open position.  When the timer timed out, the polarity of the motor drive reverses.  When the shutter flapper is fully closed, the motor again stalls and power is turned off power to the motor. 

http://www.micromo.com/ miniature gear motors

Click on Drawing Below to view PDF version of Schematic
Coin Operated Telescope Circuit Designed by Dave Johnson


Dave's Circuits by Category
eMail David A. Johnson, P.E. about this circuit


Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches

 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |   
Privacy Policy

Discovercircuits.com endeavors to credit original designers.   Please alert us by eMail so we can
delete links to material that have been copied without your permission
.   Thank you.

Copyright of all original material on this website is the property
of David A. Johnson, P.E. (Dave Johnson & Associates ) unless otherwise noted.  

Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.
All material is provided "as is" without guarantees or warranty of any kind, either expressed or implied.