Platform power requirements and sensor choice

[RoboDoig]

In the current design document the strategy for providing power to sensors and valves on board the platform is to route a power line through the rotary joint (up to 24V, 2A) which can then be split into separate power lines by a linear regulator board on the platform.

One issue that may arise is if we use devices with large differences in power requirement, e.g. a 24V solenoid and a 5V lick sensor, is that stepping down this voltage on board the platform may result in significant electrical noise that could affect electrophysiological signals, as well as some generated heat that must be dissipated.

This issue arises from the assumption that 12-24V reward valves will be used on the platform. If onboard actuators are only for dispensing gravity-fed water rewards then we can use 5V solenoids and avoid on board power regulation altogether.

Questions related to this:

1. Are 5V actuators (solenoids etc.) acceptable, or should we plan for higher voltage components being on board the platform? What is the current preferred valve model?
2. Is there a preferred lick detector in use? Is a photodiode beam-block solution acceptable? Capacitive sensors may also induce some electrical noise.

[RoboDoig]

@ederancz - the power step down will actually not be an issue, since we will have a free 12V line through the slip-ring to the sensory board so we can easily use 12V solenoids.

Re: lick detection, my assumption is that this will be something like a standard 5V beam-break detector that can be directly powered from the Harp board and we just need to read a voltage signal. Just want to double check that is correct?

[ederancz]

@RoboDoig, perfect. Re: valves: we have been using LEE valves (same as Andreas, https://www.theleeco.com/product/lhd-series-2-3-way-control-solenoid-valves/), I think they are 5V? Re: lick detection: correct (but we may want to revisit capacitive detection, as it is less bulky in front of the animal, so it blocks less of the visual field. Would it be too difficult to add this to the HARP device as well?

[RoboDoig]

Ok great, yes I think there are 5, 12 and 24V options for those - so if you have existing 5V ones we can step power down, or use 12V ones directly.

I believe either lick sensor could be used interchangeably on the HARP device, since for both those sensors we just need ~5V power and to read a voltage signal.

@davidpalma666

[RoboDoig]

@ederancz Just want to check something about the LEE valves. We initially chose them for the rapid open-close cycle which required a spike-and-hold driver - is that a requirement in your setup as well? Have you been using the spike-and-hold valve drivers?

[ederancz]

@RoboDoig I have very little practical experience with it, built it and tried it a few times, but not extensively. And no, we did't use a spike-and-hold driver. TBH I am happy with alternative solutions if available off the shelf.

[RoboDoig]

Closing this issue as we have tested all relevant sensors and valves