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I need some help designing a circuit for a timelapse slider. Please bear in mind i am a beginner with electronics, so have mercy!

The motor will be pulling a trolley (very slowly) along a set of rails while a camera on the trolley takes pictures at certain intervals. The effect is used so that in the footage the camera will move slowly while time is moving very quickly (bad explanation). Some examples of this can be seen in this video - https://www.youtube.com/watch?v=ZwzY1o_hB5Y

The DC motor i have is rated at 12V 0.06A 4RPM. Its a high torque geared motor.

Currently i use the motor with a AA (1.5V) battery which moves the trolley 0.5 metres every hour. The trolley is attached to the motor by a timing belt and pulleys (which can be seen in the image below). This is ok but i want the option to increase the speed as well as other features. timing belt and pulleys

Features Wanted

-ON/OFF switch
-option to vary speed (potentiometer?)
-direction switch
-removable battery - 9V preferred
-proximity switches - one on each side of the slider to stop the trolley from being pulled too far
-Ideally i would like the components to fit onto a space the size of the black piece of wood shown in the last photo here.(roughly 170x90mm)
-possibly a battery life display (that could be turned off to conserve battery)

Some Key questions

Is it possible to build my own circuit for under £15 ?
How long would a 9V battery (Duracell) last in this setup?
Will powering the motor with a lower voltage than its rated for break the motor?

Any answers (or questions) are welcome. Thank you for reading all the way down here!

Below are some pictures of my current setup
timelapse slider
timelapse slider 1
timelapse slider 2

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  • \$\begingroup\$ Welcome to SE, Fred. If you read the help section you'll see that shopping questions are not allowed so you should edit your question to remove those and stick to design questions. Generally a stepper motor will be much better for what you want as you can generate precise moves over a range of speeds. Search for "Arduino stepper time-lapse rig" or similar. \$\endgroup\$ – Transistor Feb 29 '16 at 22:45
  • \$\begingroup\$ @transistor - Thanks for the quick response and advice on posting. Ive just had a look at an arduino setup and that is basically what i want. But its out of my price range to buy an arduino unit and another motor. Also i think an arduino unit might be overkill for what i want to do considering i might be able to complete this using only switches and a potentiometer. Thanks again for your input though and please correct me if im naive about what i want to do. \$\endgroup\$ – Fred T Feb 29 '16 at 23:05
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DC motors will run at a speed set by the supply voltage. Speed will drop as the motor is loaded but the resultant increase in current will give more torque tending to bring it back up to nominal speed for that voltage.

Powering from a lower voltage will not break the motor.

schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. 8-speed motor control with forward/reverse and limit switches.

enter image description here

Figure 2. 12-way rotary switch.

Using eight 1.5 V batteries and a 12-way rotary switch you can create the 8-speed motor control circuit shown in Figure 1.

  • Set the stop tab on the switch so that there are nine positions available.
  • Leave position 1 as the 'OFF' position and wire up the next eight positions as shown in Figure 1.
  • The limit switches will stop motion at the end of travel so you can leave the unit unattended.
  • The FWD/REV switch ...

Note that using anything other than full voltage will cause the cells to run down unevenly but you can address this by swapping out BAT1 with BAT8, etc. to even out the life.

To work out battery life look up the mAh of the battery, measure the current into your motor (mA) and lifetime in hours = mAh / mA. (The milli-amps cancel out leaving you with hours.)

Get the 'break before make' version of the switch. This version prevents momentary shorting of, for example, BAT4 as you switch from SW4 to SW5.

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  • \$\begingroup\$ Thankyou so much, this is exactly what i was looking for. I do have one question though; when looking to buy components do i need to be looking for a certain power rating or will the power in the circuit be low enough not to worry about it. Thankyou again! \$\endgroup\$ – Fred T Feb 29 '16 at 23:32
  • \$\begingroup\$ For switches you need to consider their voltage rating (what voltage they can switch - usually determined by the contact gap, amongst other things) and the current rating (because of the heating effect of the current on the contact resistance). 12 V won't be a problem with any normal switch. See Maplin for an example of the switch. Read the spec. and (homework) let me know if you think it is adequate for your application. ;^) \$\endgroup\$ – Transistor Feb 29 '16 at 23:39
  • \$\begingroup\$ Thanks for your help. Im getting the components from maplin, and the battery holders from ebay. The 12 way switch is perfect for my application. Im also getting a DPDT toggle switch for the forward/reverse function and 2 push to break switches for the limits. Hopefully i can put together the circuit :) \$\endgroup\$ – Fred T Mar 1 '16 at 17:48
  • \$\begingroup\$ Probably the hardest part will be making the individual connections to the battery terminals. If you can file or sand the contacts / springs a bit you may be able to solder wires on without destroying the holder! Have fun. \$\endgroup\$ – Transistor Mar 1 '16 at 18:42
  • \$\begingroup\$ Ive ordered 8 individual battery holders with wires already attached to try and make it easier for myself. Thanks, I will try! \$\endgroup\$ – Fred T Mar 1 '16 at 18:52

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