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Forum Index : Electronics : Using a 555 as a MOSFET driver
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
This popped up on my Youtube feed. I've have terrible luck with using MOSFET's on PWM for heavy loads, so it caught my attention. A simple solution, and always have a few 555's in the drawer. NE555: The MOSFET Driver That Time Forgot (Until Now!)https://www.youtube.com/watch?v=FKqkRDM0Al0 Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| -dex- Regular Member  Joined: 11/01/2024 Location: PolandPosts: 99 |
Hi, While browsing the back shed while having my morning coffee at work, I came across your post, and since I was modifying a device that I added a MOSFET as the actuator, I decided to test the circuit. Yes, I confirm it's simple and effective, 555 is the IC standing there   |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Cool, glad to see this worked. I'm yet to try it, need to buy a few spare 555's. Here's a grab from the video if anyone cant access youtube, but I highly recommend you watch the video, goes into some good detail.  Glenn Edited 2024-09-20 09:20 by Gizmo The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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phil99 Guru  Joined: 11/02/2018 Location: AustraliaPosts: 2129 |
A little trap when using pin 4 (reset) as an input. Different makers use different threshold voltages. For most it is seems to be 0.6 to 1V above Gnd. But I have encountered a few that use 0.5V below Vcc. ie. for a 12v supply it switches at 11.5V. Very annoying! |
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Zathros Newbie  Joined: 20/09/2024 Location: United StatesPosts: 3 |
There is another not so well known gotcha when using the reset pin as an input. Some variations of the chip do not properly respond to reset. Reset is supposed to override all other inputs. On some versions of the parts threshold, pin 6 overrides reset. In this case the output will never go high. The fix is to connect both trigger (2) and threshold (6) to ground. This connection should work for all variations of the 555. I have a quanity of NE555 timers that only work if threshold (6) is connected to gnd.  Gary |
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