LED's flash only singly, never more than 1 at a time. Individual LED flash duration < 1sec , at least 5 min interval.
Max output events occurring at one time - 3 relays and 1 LED. Relay max durations 1-4 sec, at least 5 min interval for a relay.
Very low circuit use time and relay cycles - maybe 20 cycles over 2 hrs/day, 1-2 days/month.
Two SLA batteries are available...both can be used: 12VDC,7AH and 6VDC, 7AH
Circuit questions please(see attachment):
Need 5VDC for relays. Best V reg to use? Max 3 relays activated at once, ~80mA each, say 300mA maximum. (Note - 6V SLA max of 7V exceeds max V spec for relay)
Per spec, need 7-12VDC for Mega? Is that spec for the power jack only?
Can 5-8VDC be input to board Vin pin? Or is that pin for a regulated 5V only?
General Q - otherwise, does circuit look OK overall?
Leo, Thank you.
Circuit will be run only 2-3hrs at a time, so Mega draw is OK.
I have the 5v relay boards. Maybe I should consider going to mosfets instead of getting 12V relays.
Other stuff looks OK I hope.
Best,
Dan
Thank you for the feedback.
Here is the latest version of the schematic as tested.
I didn't know the 5V power pin on the Mega board was for input...thought that was output, per this info on the Mega:
"The power pins are as follows:
Vin. The input voltage to the board when it's using an external power source (as opposed to 5 volts from
the USB connection or other regulated power source). You can supply voltage through this pin, or, if
supplying voltage via the power jack, access it through this pin.
5V. This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with
power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-
12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We
don't advise it."
I have plenty of room, so having both a 5V and 8V reg as shown is not a problem.
The relay board worked fine - only three relays wired and tested.
Only 100R CL resistors for LEDs? What color? Red's Vf is only about 1.8 to 2V, so 30 mA from output pins, thats pushing it.
Think I would sacrifice a nickel's worth of eye candy for a dollar's worth of reliability and longevity.
outsider:
Only 100R CL resistors for LEDs? What color? Red's Vf is only about 1.8 to 2V, so 30 mA from output pins, thats pushing it.
Think I would sacrifice a nickel's worth of eye candy for a dollar's worth of reliability and longevity.
CL resistors????
Ultrabright Yellow T1-3/4, 3-3.3V. Usually run them w/100R from 6V with no issue. These will flash only 0.270 sec once maybe every 10 min. during a 2-3 hr use session, maybe 6 to 8 times a year. Mega pins rated at 40mA and these LEDs fire one at a time, less than 20mA at 5V supply. At 50 cents a pop, not too worried.
