Hey all,
I'm actuating a bunch of dc latching solenoids for irrigation that were once part of battery timer units. I've hooked up arduino -> shift registers -> l293d and have one solenoid per channel.
Solenoids are 9-12VDC , 5-10ohm (can't find spec. sheet but similiar solenoids are around this resistance). I'm running them at 12V because there will be large voltage drop on some of the irrigation lines.
I was getting all worked up about the l293d overheating (some really hot and I burnt one) and was planning on piggybacking 2 extra l293d on each to get up to 1.8 A per channel , then I realized that these solenoids are normally powered by battery, and that the click that they are making when I have them hooked to a 1.2A power supply is way louder then the tiny click I hear with the 9v alkaline battery turning them on/off .
A. My local electronics store only has up to 1/2 watt resistors, so I was wondering if I put a bunch of 1/2 watt resistors in parallel (20 maybe?) if it would be sufficient to limit the current to the solenoid so I don't need the extra l293d's.
B. If so, what ohm value should I start with. Does 20x 1k ohm 1/2 watt sound right? I can either take off / add them and make sure the l293d isn't getting warm.
C. All the solenoids have a common ground (terminal) so will putting current limiting resistors on this one line fix all of them (I'm only ever powering one at a time) , or am I completely wrong about doing things this way?
Any help is much appreciated,
-tekgen
I'm actuating a bunch of dc latching solenoids for irrigation that were once part of battery timer units. I've hooked up arduino -> shift registers -> l293d and have one solenoid per channel.
Solenoids are 9-12VDC , 5-10ohm (can't find spec. sheet but similiar solenoids are around this resistance). I'm running them at 12V because there will be large voltage drop on some of the irrigation lines.
I was getting all worked up about the l293d overheating (some really hot and I burnt one) and was planning on piggybacking 2 extra l293d on each to get up to 1.8 A per channel , then I realized that these solenoids are normally powered by battery, and that the click that they are making when I have them hooked to a 1.2A power supply is way louder then the tiny click I hear with the 9v alkaline battery turning them on/off .
A. My local electronics store only has up to 1/2 watt resistors, so I was wondering if I put a bunch of 1/2 watt resistors in parallel (20 maybe?) if it would be sufficient to limit the current to the solenoid so I don't need the extra l293d's.
B. If so, what ohm value should I start with. Does 20x 1k ohm 1/2 watt sound right? I can either take off / add them and make sure the l293d isn't getting warm.
C. All the solenoids have a common ground (terminal) so will putting current limiting resistors on this one line fix all of them (I'm only ever powering one at a time) , or am I completely wrong about doing things this way?
Any help is much appreciated,
-tekgen
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