# Aeroponics - Can plants grow without soil? **URL:** https://metastudio.org/t/aeroponics-can-plants-grow-without-soil/829 **Category:** STEM Chat **Tags:** plant-growth, aeroponics, nutritional-control, horticulture, tissue-culture **Created:** [July 14, 2019, 7:48pm UTC](https://metastudio.org/t/aeroponics-can-plants-grow-without-soil/829 "2019-07-14T19:48:10Z") **Posts on this page:** 1 **Showing post:** 14
### Author: ![jtd](https://metastudio.org/user_avatar/metastudio.org/jtd/32/244_2.png) [@jtd](https://metastudio.org/u/jtd) #### Post date: [December 17, 2020, 7:55pm UTC](https://metastudio.org/t/aeroponics-can-plants-grow-without-soil/829/14 "2020-12-17T19:55:33Z")
ATTINY2313 micro running aeroponic pump. Cycle time 30 sec. Duty cycle 50%. JT D, [17.12.20 18:29] On the left is a pc psu that powers the board and pump. Pump controlled with relay. Wouldn’t a MOSFET be preferable? JT D, [17.12.20 18:30] Timer is interrupt driven. @Kush\_agra\_wal, [17.12.20 18:38] Relay would give perfect isolation between controller and pump hence i guess in this case relay will be a better option and also the selection would depend on how much current is to be switched that depends on pump and i think relay can switch or control more current than MOSFET? Kushagra Agrawal, [17.12.20 18:39] Not sure of it​👆 JT D, [17.12.20 18:53] [In reply to Kushagra Agrawal] True that isolation is excellent. The relay’s inherent isolation is 3.5kv. But PCB layout is very important to achieve that. JT D, [17.12.20 18:54] Current draw is 8A. Voltage is 12v. JT D, [17.12.20 18:56] There is a rs485 driver so that i can connect to a server like Raspberry PI. Should i use rs232 instead? Kushagra Agrawal, [17.12.20 19:15] [In reply to JT D] But then to draw this max amount of current we would need a high gate voltage to control the switching so it may be possible that micro controller been used won’t supply this through its I/O port? Means again it would need configuration, if possible, to be used? Kushagra Agrawal, [17.12.20 19:17] And in this aeroponic farm the data is collected from multiple points or a single point? JT D, [17.12.20 20:22] [In reply to Kushagra Agrawal] Multiple. JT D, [17.12.20 20:32] [In reply to Kushagra Agrawal] To drive the relay we use a transistor. The relay requires 12v. The transistor is TIP122 connected to 12 v. So a gate drive of 12 v is quite feasible. We will save space and have a far longer life for a transistor, but it probably wont save us any money. #design optimisation- cost, space, reliability, manufactureability, serviceability… If we were making several thousand, it would definitely be a MOSFET. Kushagra Agrawal, [17.12.20 20:42] [In reply to JT D] Then rs485…cause i think with rs232 you can connect only one device. Like rs232 was used with db9 cable for printer and computer connection. Kushagra Agrawal, [17.12.20 20:45] And selection would also depend on basis which proto is faster among rs485 and rs232 as data would be transferring. JT D, [17.12.20 21:01] [In reply to Kushagra Agrawal] Yes. RS485 is a balanced line multi drop system. Speed will be slower than a RS232 as it is half duplex - unless we separate the tx and rx lines. However the amount of data is very sparse. So a very low speed would be perfectly ok. @Anool jokingly suggested a 555 timer Anool Mahidharia, [17.12.20 18:54] [In reply to JT D] Looking good. Although, a 555 would have done the job !! 😉 JT D, [17.12.20 19:04] [In reply to Anool Mahidharia] 🙂. Yes. Unfortunately water level and rs485 link are likely to mess up a 555, though we could implement a 556 level control. Anool Mahidharia, [17.12.20 19:05] LOL, just kidding. gotta get in a 55 joke at every opportunity. JT D, [17.12.20 19:10] [In reply to Anool Mahidharia] 😁. But seriously a fully discrete transistor implementation would be fun. JT D, [17.12.20 19:11] After all blokes are building cpus with transistors 😉 --- _[View the full topic](https://metastudio.org/t/aeroponics-can-plants-grow-without-soil/829)._