DocMcC
New Member
Hi all,
Finally gone out of beta testing and into first "run" of the frozen food feeder I have been working on over the last few months.
Essentially started with a travel mug, added a raspberry pi and a few bits and went from there.
Food recipe I am using I got off the following thread: Automatic Frozen/refrigerated food dispenser | REEF2REEF Saltwater and Reef Aquarium Forum
Starting point: stripped down:
upgraded the peltier cooler and added a massive CPU heatsink / fans.
Also added a dosing pump (Atlas scientific "Large" dosing pump) - this bit was not cheap...
insides of a standard stirrer you can get cheaply on amazon
Raspberry Pi Zero W2 - via python
4 relays (only really need 2)
some buck converters to change the voltages (power supply is a 15amp 12v) as the pump works on 24v, the peltier & fans on 12v, raspberry pi on 5v and the mixer on 9v
Designed and 3d printed the housing using Sketchup and a Bambu Labs Carbon printer - hence needed to be in 2 parts as the printer was not big enough to do the unit in one go! (Bi-colour as it was intially all in black but had to reprint the front as the dosing pump stopped the food cup being removed!)
Some simple specs
1) Keeps the food at betweein -1.5 and -0.25 degrees (even when the ambiant temp is 37 degrees!!!)
2) So far I am testing 28 cubes to be delivered in 7 batches over 14 days - reckon it could take 50+ cubes BUT keeping it fresh might be a problem.
3) Self cleans the tubes! (run the dosing pump backwards)
4) pushes pertinant details e.g. temps etc to phone for monitoring purposes
5) Stops feeding totally if temp goes up above 15 degrees until it is reset - need to change this to being "over x degrees for y minutes"
6) can input the number of feeds and time (days) between feeds and it will calculate the correct amount to dose at each feed.
Way it works is:
most of the time it is just checking the temp and turning on/off the peltier and controlling the speed of the fans.
At feeding time:
1) stirs food for 10 seconds (don't want to break it up too much
2) doses the correct amount of food - day 1 is 1/7th, day 2 is 1/6th etc - dependent on the number of feeds selected
3) waits and then replaces the amount of food with tank water - cleans the tubes etc
4) waits x days and repeats the process (x is set by the user)
Code is written in python (not many lines - actually quite simple)
My only concerns are:
1) how long the food will keep since I am diluting it after every feed
2) the amount of energy it takes to keep the food at just below freezing (approx 100W!!) - only to be used at "holiday" time
Will try different peltier modules - currently using a 12710, 12712 did not work at all (I don't fully understand the laws of thermodynamics followed by these units but I think it might have something to do with the heatsink not being big enough to take away all the heat on the hot side so this "corrupts" the cold side making it less effective than a smaller unit) and 12706 could not keep it reliably at the correct temp. Have ordered a stacked unit from China - this may work more efficiently. other option is to try a 12708 or 12709.
Happy to hear any thoughts/questions etc. especially around the "freshness" of the food after 2 weeks.
Also if anyone wants to share info,
more info, links to parts etc let me know.
Finally gone out of beta testing and into first "run" of the frozen food feeder I have been working on over the last few months.
Essentially started with a travel mug, added a raspberry pi and a few bits and went from there.
Food recipe I am using I got off the following thread: Automatic Frozen/refrigerated food dispenser | REEF2REEF Saltwater and Reef Aquarium Forum
Starting point: stripped down:
upgraded the peltier cooler and added a massive CPU heatsink / fans.
Also added a dosing pump (Atlas scientific "Large" dosing pump) - this bit was not cheap...
insides of a standard stirrer you can get cheaply on amazon
Raspberry Pi Zero W2 - via python
4 relays (only really need 2)
some buck converters to change the voltages (power supply is a 15amp 12v) as the pump works on 24v, the peltier & fans on 12v, raspberry pi on 5v and the mixer on 9v
Designed and 3d printed the housing using Sketchup and a Bambu Labs Carbon printer - hence needed to be in 2 parts as the printer was not big enough to do the unit in one go! (Bi-colour as it was intially all in black but had to reprint the front as the dosing pump stopped the food cup being removed!)
Some simple specs
1) Keeps the food at betweein -1.5 and -0.25 degrees (even when the ambiant temp is 37 degrees!!!)
2) So far I am testing 28 cubes to be delivered in 7 batches over 14 days - reckon it could take 50+ cubes BUT keeping it fresh might be a problem.
3) Self cleans the tubes! (run the dosing pump backwards)
4) pushes pertinant details e.g. temps etc to phone for monitoring purposes
5) Stops feeding totally if temp goes up above 15 degrees until it is reset - need to change this to being "over x degrees for y minutes"
6) can input the number of feeds and time (days) between feeds and it will calculate the correct amount to dose at each feed.
Way it works is:
most of the time it is just checking the temp and turning on/off the peltier and controlling the speed of the fans.
At feeding time:
1) stirs food for 10 seconds (don't want to break it up too much
2) doses the correct amount of food - day 1 is 1/7th, day 2 is 1/6th etc - dependent on the number of feeds selected
3) waits and then replaces the amount of food with tank water - cleans the tubes etc
4) waits x days and repeats the process (x is set by the user)
Code is written in python (not many lines - actually quite simple)
My only concerns are:
1) how long the food will keep since I am diluting it after every feed
2) the amount of energy it takes to keep the food at just below freezing (approx 100W!!) - only to be used at "holiday" time
Will try different peltier modules - currently using a 12710, 12712 did not work at all (I don't fully understand the laws of thermodynamics followed by these units but I think it might have something to do with the heatsink not being big enough to take away all the heat on the hot side so this "corrupts" the cold side making it less effective than a smaller unit) and 12706 could not keep it reliably at the correct temp. Have ordered a stacked unit from China - this may work more efficiently. other option is to try a 12708 or 12709.
Happy to hear any thoughts/questions etc. especially around the "freshness" of the food after 2 weeks.
Also if anyone wants to share info,
