Hi,
I'm just starting out getting into various Arduino and electronics projects and am trying to start simple as I learn. In this particular case I was trying to make a battery powered setup that could control one of my garden watering valves. The particular valve is a latching solenoid and requires a pulse of +24v to open and -24v to close. I got everything working fine running from 3 AA, a 3.3v Arduino, 2 Voltage Booster boards (one to do 24V and the other 5V) and a board with 2 5V relays. I'm trying to take it slow and use pre-made components/boards as I learn and get the various parts and equipment needed over time and then optimize.
Anyway, the voltage regulators I got are these:
http://www.amazon.com/dp/B00C9179WK
But they seem to draw 10-15mA when doing nothing which isn't great for battery consumption. They are only really needed when the valve needs to be switched on or off and otherwise aren't needed. So I tried putting in PN2222 NPN transistors on the ground leg of the booster board to switch them on and off. I believe the current requirements don't exceed the PN2222 specs. This works but not very reliably. If it's been off for a long time and I power the system the 5V relay system sometimes doesn't work (and therefore the 24V system isn't used). Other times it will but it seems to happen more when off for a long time.
I haven't found a good answer but from what I gather a voltage regulator/booster is not really meant to be continually switched on and off completely. Is this correct? I think some of the problem is that there is a big inrush current upon start up of the booster circuit to charge it's capacitors and I think this destabilizes the system somehow. Also since I'm only keeping the booster on for the duration of sending out the pulse (< 0.5s) I think it sometimes doesn't have enough time to stabilize.
I don't have a good diagram to upload yet but I was wondering if someone had some thoughts on switching on and off these kinds of circuits. Maybe I should try to use a PNP on the positive leg, or maybe I should be looking at something completely different. There are a lot of voltage boosters out there that can be put together (some have some shutdown/standby inputs) but I didn't find something I could just plug in as easily. Eventually I want to dive into it and put one together in a v2 version of the circuit (and then a v3 with no relays but mosfets) but I would still have some sort of voltage booster in the system which would ideally be off when not in use.
Any thoughts or direction?
Thanks.
I'm just starting out getting into various Arduino and electronics projects and am trying to start simple as I learn. In this particular case I was trying to make a battery powered setup that could control one of my garden watering valves. The particular valve is a latching solenoid and requires a pulse of +24v to open and -24v to close. I got everything working fine running from 3 AA, a 3.3v Arduino, 2 Voltage Booster boards (one to do 24V and the other 5V) and a board with 2 5V relays. I'm trying to take it slow and use pre-made components/boards as I learn and get the various parts and equipment needed over time and then optimize.
Anyway, the voltage regulators I got are these:
http://www.amazon.com/dp/B00C9179WK
But they seem to draw 10-15mA when doing nothing which isn't great for battery consumption. They are only really needed when the valve needs to be switched on or off and otherwise aren't needed. So I tried putting in PN2222 NPN transistors on the ground leg of the booster board to switch them on and off. I believe the current requirements don't exceed the PN2222 specs. This works but not very reliably. If it's been off for a long time and I power the system the 5V relay system sometimes doesn't work (and therefore the 24V system isn't used). Other times it will but it seems to happen more when off for a long time.
I haven't found a good answer but from what I gather a voltage regulator/booster is not really meant to be continually switched on and off completely. Is this correct? I think some of the problem is that there is a big inrush current upon start up of the booster circuit to charge it's capacitors and I think this destabilizes the system somehow. Also since I'm only keeping the booster on for the duration of sending out the pulse (< 0.5s) I think it sometimes doesn't have enough time to stabilize.
I don't have a good diagram to upload yet but I was wondering if someone had some thoughts on switching on and off these kinds of circuits. Maybe I should try to use a PNP on the positive leg, or maybe I should be looking at something completely different. There are a lot of voltage boosters out there that can be put together (some have some shutdown/standby inputs) but I didn't find something I could just plug in as easily. Eventually I want to dive into it and put one together in a v2 version of the circuit (and then a v3 with no relays but mosfets) but I would still have some sort of voltage booster in the system which would ideally be off when not in use.
Any thoughts or direction?
Thanks.