I am connecting five 12V relay coils in parallel to switch five different loads. Is it necessary to have fly-back diode for each relay coil or just one 1N400x diode in parallel is sufficient? Each coil is 300 ohms.
-bhavj
-bhavj
Hello,I am connecting five 12V relay coils in parallel to switch five different loads. Is it necessary to have fly-back diode for each relay coil or just one 1N400x diode in parallel is sufficient? Each coil is 300 ohms.
[email protected] schrieb:
Hello,
the current through one coil is 40 mA, the five coils take 200 mA. A
1N400x is good for 1 A. If these five relays are not far away from each
other, only diode will do in my opinion. The current flowing through the
diode should not be much larger than the current flowing through all
coils together.
Bye
Make sure you use the low-voltage one, 1N4001. Higher-voltage diodes of
that series have long turn-on delays, so they aren't much good for
suppressing inductive kicks.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
The 1N4001 should be fine, but do use at least a 60V transistor to drive
the relays.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
I am connecting five 12V relay coils in parallel to switch five different loads. Is it necessary to have fly-back diode for each relay coil or just one 1N400x diode in parallel is sufficient? Each coil is 300 ohms.
I am connecting five 12V relay coils in parallel to switch five different loads. Is it necessary to have fly-back diode for each relay coil or just one 1N400x diode in parallel is sufficient? Each coil is 300 ohms.
-bhavj
I am connecting five 12V relay coils in parallel to switch five different loads. Is it necessary to have fly-back diode for each relay coil or just one 1N400x diode in parallel is sufficient? Each coil is 300 ohms.
-bhavj
Here is the schematic I quickly drafted. All the 5 coils and fly back
diode are in parallel and will be connected to 12V_RLY_COIL.
https://picasaweb.google.com/106331...vh_NXi3AE&feat=directlink#5912784366042056882
John Larkin said:The OP should post his schematic. I've seen interesting things, like
putting TTL levels into a base and expecting 12 volt swing at the
emitter.
Sorry, you have just been demoted to SCI Electronics Basic!
Harry
Why is it that nobody helps the guy, rather than just letting himIs that supposed to be funny?
Why is it that nobody helps the guy, rather than just letting him
know you're all smarter than him.
The more common method to drive a relay is;
+12v to one side of relay, other side of relay goes to the collector of
an NPN transistor, emitter of transistor goes to ground. Put a 1k
resistor in series with base of transistor and apply your 3.3v the 1K
resistor.
Install diode across relay.
Is there a reason you don't want to do it that way?
Mikek
*1K value can be adjusted.
Nah, your average 12V relay will pull in around 9V. 11.3ish is fat city.
Looks like he wants to switch the coils and regulate the coil voltage
down to 12. 18V is a bit much, 2.2x the normal coil dissipation.
I scribbled a few circuits, until I ran out of paper.
https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/Relay_Drivers.pdf
Oh, 1117s need an output cap.
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
I scribbled a few circuits, until I ran out of paper.
https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/Relay_Drivers.pdf
Oh, 1117s need an output cap.
I've obviously led a sheltered life, since I've never seen a 12V relay
datasheet where pull-in wasn't guaranteed at well below 11.3V. Do you
have an example?
Cheers
Phil Hobbs
I like 7, assuming the firmware cooperates.