Falcon Christmas

The Lab (Technical Talk) => New Hardware Projects => Topic started by: tech1412 on November 30, 2020, 02:53:27 PM

Title: F-Amp Schematic / Component List
Post by: tech1412 on November 30, 2020, 02:53:27 PM
Does anyone happen to have or know where a schematic or component list of the F-Amp can be found. This would be primarily for troubleshooting/replacement if components get fried. I also had an idea of possibly exploring an F-Amp distro board where several F-Amps or F-Amp circuits are on a board with Phoenix connectors rather than having pigtails that need to be attached to other pigtails. Any ideas?
Thanks!
tech1412
Title: Re: F-Amp Schematic / Component List
Post by: Arti G on November 30, 2020, 04:44:42 PM
Can anyone explain principle of operation of F-Amp? Is it just galvanic isolation? I have PiCap and I have problem with ws2811 leds randomly blinking, no idea why it is happening and if F-Amp could help.
Title: Re: F-Amp Schematic / Component List
Post by: tech1412 on November 30, 2020, 06:10:49 PM
Arti G,
I am testing a fix that I received from an earlier post regarding random pixels staying on. Depending on how you hooked up your F-Amp, if anything like mine, the ground needs to be hooked up all the way back to the power supply your strand originates from. For example, with my setup I was trying to opt for individual circuits to separate one run from another after the F-amp. So I have 12VDC, Data, and GND all the way to the end of one run and then start a new run of 12VDC and GND after the F-Amp, with only the Data staying continuous. This is a mistake. The Data needs a reference ground and even though my power injection comes from the same power supply as the originating strand, the GND is broken which is causing an unreliable triggering of my pixels from the F-Amp on. My test fix is to re-insert the ground after the F-Amp so it has a continuous ground back to the power supply and forward to the new set of pixels.
To my knowledge, the F-Amp is a TTL buffer, but what style package and ratings it has I'm still looking for. Not to mention I have no clue what the other components are surrounding the F-Amp... possibly filter caps and biasing resistors, but values and types are something I'm seeking out so that I can troubleshoot if I ever need to.
Hope this helps, I know it helped me!
tech1412
Title: Re: F-Amp Schematic / Component List
Post by: Arti G on January 28, 2021, 11:15:25 AM
I think F-Amp uses something like 74HTC or FET and just increases 3,3V data levels to 5V. 

https://learn.adafruit.com/neopixels-on-raspberry-pi/raspberry-pi-wiring

https://hackaday.com/2017/01/20/cheating-at-5v-ws2812-control-to-use-a-3-3v-data-line/

https://www.electrobob.com/ws2812-level-translator/

https://hackaday.com/2016/12/05/taking-it-to-another-level-making-3-3v-and-5v-logic-communicate-with-level-shifters/

https://learn.adafruit.com/adafruit-neopixel-uberguide/best-practices

https://learn.sparkfun.com/tutorials/retired---using-the-logic-level-converter

https://www.aliexpress.com/item/1005001602599498.html

https://botland.store/led-chains-matrices/8790-pixel-boost-module-33v-5v-voltage-buffer-for-ws2812b-diodes.html

https://www.aliexpress.com/item/4000361911912.html
Title: Re: F-Amp Schematic / Component List
Post by: pixelpuppy on January 28, 2021, 02:08:25 PM
Quote from: tech1412 on November 30, 2020, 02:53:27 PMDoes anyone happen to have or know where a schematic or component list of the F-Amp can be found. This would be primarily for troubleshooting/replacement if components get fried.

I must be missing something...
Wouldn't that be similar to fixing a pixel if it gets fried?   They are low-cost disposable items.  If its fried just replace it, too much trouble and not much saved in trying to repair it.   
Title: Re: F-Amp Schematic / Component List
Post by: Poporacer on January 28, 2021, 02:21:54 PM
Quote from: pixelpuppy on January 28, 2021, 02:08:25 PMI must be missing something...
Me too? That would be like trying to fix a bad pixel. To me time is money (to an extent) the F-Amp is enclosed in epoxy and just to get to the components in order to determine what is wrong and to fix it would probably take several hours and there is a real good possibility that you could end up damaging it beyond repair in doing so.  You would have to have several components on hand that unless you purchase them in bulk will cost quite a bit more than the vendor buys them for and you will have to have the Epoxy. Cost wise you might save a couple dollars but to me saving one or two dollars but spending 6-7 hours to do so is not my idea of a cost savings? But that is just my opinion!
Title: Re: F-Amp Schematic / Component List
Post by: Arti G on January 28, 2021, 02:54:55 PM
Repairing F-Amp isn't a good idea, not worth time, but I think it is very interesting to know how it works and understand source of the problem it solves. At least interesting for DIYers like me.

It seems that problem is a low signal voltage level (3.3V) from controller (PiCap in my case) and signal voltage level drop on longer wires. See above links to read more.

And another problem is ringing from controller (video): http://falconchristmas.com/forum/index.php/topic,2115.0.html

I think that best to solve these problems will be use of translator 74LVC1T45 + schmitt trigger 74LVC1G17. Interesting would be to add galvanic isolation Adum1200/1201 and TVS diode for protection.
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