mightyconfused
- Apr 9, 2013
- 6
- Joined
- Apr 9, 2013
- Messages
- 6
Hi Guys,
Relatively new electronics newbie here - so thanks for your help
Recently I purchased several electromechanical seven segment vane displays for a project.
As you can see in the photo, each segment flips out or back by a magnetic field generated through the coil.
Each segment has only 1 coil. By changing the direction of the current impulse through the coil, you can change if the segment flips out or back.
Each coil has a resistance of 50 Ohm and requires ~ 24 V impulse to drive.
I am planning to use SN754410 chips to drive the impulse (with the logic coming from an Arduino + shift register). (SN754410 data sheet: http://docs-asia.electrocomponents.com/webdocs/0b87/0900766b80b878b5.pdf).
After doing some reading I realise that when the current across the coil is turned off, there can be quite a high reverse 'breakdown' current that I need to protect my chips against.
I am quite confused about the placement of diodes between the SN754410 and the coils to protect agains this (??)kickback current. I initially thought the diodes would be in series with the coil, but some sites suggest they should be in parallel. But if they are in parallel with the coil - how does that work when I reverse the polarity.
Can someone please give me a guiding hand. This is well over my simple head.
Thanks
Relatively new electronics newbie here - so thanks for your help
Recently I purchased several electromechanical seven segment vane displays for a project.
As you can see in the photo, each segment flips out or back by a magnetic field generated through the coil.
Each segment has only 1 coil. By changing the direction of the current impulse through the coil, you can change if the segment flips out or back.
Each coil has a resistance of 50 Ohm and requires ~ 24 V impulse to drive.
I am planning to use SN754410 chips to drive the impulse (with the logic coming from an Arduino + shift register). (SN754410 data sheet: http://docs-asia.electrocomponents.com/webdocs/0b87/0900766b80b878b5.pdf).
After doing some reading I realise that when the current across the coil is turned off, there can be quite a high reverse 'breakdown' current that I need to protect my chips against.
I am quite confused about the placement of diodes between the SN754410 and the coils to protect agains this (??)kickback current. I initially thought the diodes would be in series with the coil, but some sites suggest they should be in parallel. But if they are in parallel with the coil - how does that work when I reverse the polarity.
Can someone please give me a guiding hand. This is well over my simple head.
Thanks
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