ATO build question?
- Thread starter muggleman
- Start date
No you don't. Just make sure you stick with a low wattage pump (remember this will mean relatively low head height - only a couple of meters at max) as a high wattage runs the risk of welding cheap float switches closed!
Makes a good cheap solution and there was a simple DIY circuit posted on another forum to add a 10s cut out (if pump runs for more than 10s it cuts out the system and flashes an LED till you reset it - the 10s can be any time you fancy by changing the capacitor you use).
Tim
Makes a good cheap solution and there was a simple DIY circuit posted on another forum to add a 10s cut out (if pump runs for more than 10s it cuts out the system and flashes an LED till you reset it - the 10s can be any time you fancy by changing the capacitor you use).
Tim
skeeter_ca
Active member
If you don't want to run a relay then you need to know the amperage that your pump will pull when running, which is usually on the pump. Also you need to know the rating that the float switches can handle. A good rule of thumb is the pump should only pull 2/3rds of the rating for the float switches. That will give you a margin to safely run the pump without burning out the switches. If the pump pulls too much amperage for the float switch then a relay should be incorporated in the design.
skeeter
skeeter
Thanks for the advice guys, I hooked everything up last night but I seem to be running into a problem the pump works with no problem when it's hooked up to the 12v power supply but when I introduce the switches then the power seems to come and go! I have 6 new float switchs and have tryed them all and im still having the same problems! Can anyone help?
Here are the parts details
AC/DC Adaptor-Input AC230V 50Hz-Output DC12v 200mA
Pump-DC:5.5-12V 1-3W
Float Switch-Max Load 50W, Max Switching Voltage 100V DC, Minimum Breakdown Voltage 250V DC, Maximum Switching Current 0.5A, Maximum Load Current 1.0A, Maximum Contact Resistance 0.4 ohms,
Here are the parts details
AC/DC Adaptor-Input AC230V 50Hz-Output DC12v 200mA
Pump-DC:5.5-12V 1-3W
Float Switch-Max Load 50W, Max Switching Voltage 100V DC, Minimum Breakdown Voltage 250V DC, Maximum Switching Current 0.5A, Maximum Load Current 1.0A, Maximum Contact Resistance 0.4 ohms,
Your PSU is not powerful enough. 0.2A at 12V is only 2.4W and your pump is 3W at 12V (0.25A). Suprised it works when connected directly but even then I wouldn't run it for long as you are driving the PSU too hard. I assume the extra resistance from the float switches is too much when added in as well.
Tim
Tim
Thanks Tim, so what PSU spec would you recommend?
skeeter_ca
Active member
I would recommend at least .5amp (500ma) as a minimum. You could go anything higher and it would be ok.
skeeter
skeeter
Keep in mind those cheap ebay special floats may be rated to switch 500mA but they tend to fuse at much, MUCH lower currents. I have a hard time using them even at 100mA draw without using a relay. I don't trust them when switching a device directly (unless they are a high quality float, expect to pay upwards of $15 for a decent one). A relay is just as cheap as the floats and well worth the extra work for reliability and peace of mind, IMHO.
Float may seem to be working fine for a few days/weeks then fuse closed and cause a flood......
Float may seem to be working fine for a few days/weeks then fuse closed and cause a flood......
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