Sral's Aquarium and Reef-Pi Build

[Sral]

As mentioned in the doser-thread, I have finished my doser module:

I have also updated the circuit drawing:

I added a 470µF bypass capacitor and realized PWM dimming, in case I want this feature in the future. Note the diodes which enable me to PWM dimm two channels with one PWM signal without the channels interfering with each other. The diodes will of course mean that I can only pull the input signal to one diode drop above GND (e.g. ~0.8V) but since the same is true for the ULN2801 transistor inputs, that should effectively cancel the motor activation by the ULN2801 during the PWM's high phase.

This way I can switch the Motors on and off with a reliable GPIO, but still dim with PWM.

 

[Sral]

Tested the doser-module with a lab bench power supply before blowing up my ReefPi. I gave it both 5V and 12V and tested the motors by pulling up the signal input to VCC with a 16k resistor as I didn’t have a 3.3V signal at hand. Using this large resistor creates a 3.3V or lower on the signal input. The motors worked in both cases, even though the signal current for the 5V drive was only about 0.2mA, much lower than in the real circuit !

My Setup is starting to grow too large for my desk though

Main PI unit on the left with 2 DS18B20 temperature sensors, 12V power supply unit with relays in the middle and Doser module on the right.
GPIO Signals are carried by the gray DB9 connectors, power is carried by the yellow, red and black 4 MOLEX cables (AWG18 wire).
I2C is carried by a shielded USB cable to the small air quality sensor mentioned before, which you can see just below the power supply unit.

 

[Ranjib]

As mentioned in the doser-thread, I have finished my doser module:
View attachment 2968323
I have also updated the circuit drawing:
View attachment 2968358
I added a 470µF bypass capacitor and realized PWM dimming, in case I want this feature in the future. Note the diodes which enable me to PWM dimm two channels with one PWM signal without the channels interfering with each other. The diodes will of course mean that I can only pull the input signal to one diode drop above GND (e.g. ~0.8V) but since the same is true for the ULN2801 transistor inputs, that should effectively cancel the motor activation by the ULN2801 during the PWM's high phase.

This way I can switch the Motors on and off with a reliable GPIO, but still dim with PWM.

Looks super nice. For past 5 years I’m using only single head dosers, but now since the reefer 300 use, I feel I need more dosing heads. This housing looks awesome. I am thinking of going with off the she,f 12v pwm controller since I realized I barely change the speed, direction. And when I need it, I actualy prefer to do it with physical controls over software. But I can see the benefits of software .. specially if we do titration, I feel.

 

[Sral]

Looks super nice. For past 5 years I’m using only single head dosers, but now since the reefer 300 use, I feel I need more dosing heads. This housing looks awesome. I am thinking of going with off the she,f 12v pwm controller since I realized I barely change the speed, direction. And when I need it, I actualy prefer to do it with physical controls over software. But I can see the benefits of software .. specially if we do titration, I feel.

Yeah, thinking about changing direction with software for @Wolfw28 made me realize that it’s not very secure most of the time, so physical Switches would be better. I think there are even flip switches that allow you to switch direction seamlessly with one switch if they offer two isolated rows of 3 pins each.

what switches and PWM controller do you plan on using ?

For titration I currently can’t think of a reason to switch direction. Do you need that to get single drops accurately without spurious flow after shutoff ?

 

[Wolfw28]

Yeah, thinking about changing direction with software for @Wolfw28 made me realize that it’s not very secure most of the time, so physical Switches would be better. I think there are even flip switches that allow you to switch direction seamlessly with one switch if they offer two isolated rows of 3 pins each.

what switches and PWM controller do you plan on using ?

For titration I currently can’t think of a reason to switch direction. Do you need that to get single drops accurately without spurious flow after shutoff ?

@Sral i have an auto feeder( dosing pump) that feeds live copepods to my system. thought it would be cool to be able to reverse the flow to clear the tubing and maintain same fluid level in my feed container.

 

[Sral]

@Sral i have an auto feeder( dosing pump) that feeds live copepods to my system. thought it would be cool to be able to reverse the flow to clear the tubing and maintain same fluid level in my feed container.

Right, in that case I would definitely recommend simply using the L293D circuit from the guide. You can get some off Amazon or other pages, like Win-source.

Or if you do not care about PWM dimming the speed, just use the L9110 from Adafruit. The datasheet mentions the wiring on the last page, if you need any help, let me know. The IC also includes kickback diodes already as well. You will need 2 GPIO pins, one to activate forward, one to activate backward. If you trigger both accidentally the motor stands still ^^

 

[Sral]

As you can see in my DIY LED Controller/Driver thread, I have more or less finished my dimmable LED driver unit. It basically runs on a PCA9685, connected to my 5V I2C-network with a shielded USB-A cable and supplied by the lamps 24V power supply:

The whole setup is getting larger and larger though and I'm still missing my sensor module and camera ... both will likely add another one of these medium-sized boxes