# SnailScanToo or 2

**URL:** <https://forums.kinograph.cc/t/snailscantoo-or-2/2548>\
**Category:** Machine Design\
**Created:** [June 8, 2023, 9:51am UTC](https://forums.kinograph.cc/t/snailscantoo-or-2/2548 "2023-06-08T09:51:59Z")\
**Posts on this page:** 1\
**Showing post:** 83

<div class="post-metadata">

**Author:** ![cpixip](https://forums.kinograph.cc/user_avatar/forums.kinograph.cc/cpixip/32/852_2.png) [@cpixip](https://forums.kinograph.cc/u/cpixip)\
**Post date:** [January 22, 2024, 8:35pm UTC](https://forums.kinograph.cc/t/snailscantoo-or-2/2548/83 "2024-01-22T20:35:47Z")

</div>

> [@Alexi\_Maschas](#):
>
> Is there a reason you chose not to use standard driver with PWM or analog dimming?

LEDs are fast enough to follow the PWM signal. That is, there brightness changes from 100% LED intensity when the PWM is at 100% to something close to 0% intensity when the PWM is at 0%. Usually fast enough (several kHz at least) that your eyes do not notice, but a camera with a sufficient short exposure time will notice this anyway. Of course, you do want to avoid that.

If “Analog dimming” refers to the old dimming unit in AC circuits: they have the same problem, as they are working with chopping frequencies of 50 Hz (most of the world) or 60 Hz (US).

One way out is to have a truely analog current source; one way to implement such a thing is a DAC which drives a op-Amp paired with a beafy FET. An old schematic of such a setup can be found [here](https://forums.kinograph.cc/t/new-raspi-hqcam-a-question-of-white-balance/1793/3).

---

_[View the full topic](https://forums.kinograph.cc/t/snailscantoo-or-2/2548)._