12v/30 amp car relay+1n4148 diode? So yeah, the title says pretty much everything... I was thinking of speeding up my heatbed heating time and I read that a relay is the way to go. I happen to have a 12v 30a car relay and a 1n4148 diode in my spare box, and I wanted to use it as a flyback diode. Btw, I have a ramps 1.4 and a 12v 30 amp psu. Thanks a lot!! https://reprap.org/forum/read.php?4,629591,629591#msg-629591 Mon, 14 Sep 2026 01:41:43 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,629591,630556#msg-630556 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,630556#msg-630556 3/s?]]> JamesK Reprappers Tue, 23 Feb 2016 07:13:51 -0500 https://reprap.org/forum/read.php?4,629591,630416#msg-630416 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,630416#msg-630416 Roger123D Reprappers Mon, 22 Feb 2016 22:06:49 -0500 https://reprap.org/forum/read.php?4,629591,630024#msg-630024 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,630024#msg-630024 the_digital_dentist Reprappers Mon, 22 Feb 2016 02:22:21 -0500 https://reprap.org/forum/read.php?4,629591,630002#msg-630002 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,630002#msg-630002
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elwood127
I stand corrected. Thanks DD. Are caps ever used for this?

A cap would make it worse IMHO. The flyback diode has an much lower resistance.]]> o_lampe Reprappers Mon, 22 Feb 2016 01:13:40 -0500 https://reprap.org/forum/read.php?4,629591,629996#msg-629996 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629996#msg-629996 elwood127 Reprappers Mon, 22 Feb 2016 00:45:36 -0500 https://reprap.org/forum/read.php?4,629591,629979#msg-629979 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629979#msg-629979
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the_digital_dentist
Some automotive relays have shunt rectifiers built in- if the relay has a polarity marking that may be why. Check the relay's spec sheet.

Just checked it, no rectifiers or polarity markings, just a common mech relay.

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the_digital_dentist
I'd probably look for a diode that's intended to be used as a rectifier in a power supply, not a small signal switching diode like the 1N4148.

I have a fr157 and a fr102 diodes I desoldered from an old atx psu a while ago. Would any of those two be okay?

BTW, thanks everybody for your patience!!]]> mato84 Reprappers Sun, 21 Feb 2016 22:15:12 -0500 https://reprap.org/forum/read.php?4,629591,629973#msg-629973 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629973#msg-629973
Some automotive relays have shunt rectifiers built in- if the relay has a polarity marking that may be why. Check the relay's spec sheet.]]> the_digital_dentist Reprappers Sun, 21 Feb 2016 21:12:43 -0500 https://reprap.org/forum/read.php?4,629591,629962#msg-629962 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629962#msg-629962 mato84 Reprappers Sun, 21 Feb 2016 19:30:33 -0500 https://reprap.org/forum/read.php?4,629591,629919#msg-629919 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629919#msg-629919 forums.reprap.org]]]> elwood127 Reprappers Sun, 21 Feb 2016 16:17:50 -0500 https://reprap.org/forum/read.php?4,629591,629916#msg-629916 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629916#msg-629916
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mato84
With all the noise the printer makes, I don´t mind the clicking very much. What do you mean I don´t need the diode?

The control wires that fed the heatbed activate the relay. The extra power supply feeds the heatbed directly through the other side of the relay.]]> elwood127 Reprappers Sun, 21 Feb 2016 16:10:25 -0500 https://reprap.org/forum/read.php?4,629591,629911#msg-629911 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629911#msg-629911 JamesK Reprappers Sun, 21 Feb 2016 16:01:52 -0500 https://reprap.org/forum/read.php?4,629591,629906#msg-629906 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629906#msg-629906 mato84 Reprappers Sun, 21 Feb 2016 15:51:04 -0500 https://reprap.org/forum/read.php?4,629591,629895#msg-629895 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629895#msg-629895 JamesK Reprappers Sun, 21 Feb 2016 15:25:00 -0500 https://reprap.org/forum/read.php?4,629591,629885#msg-629885 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629885#msg-629885 I´ts interesting what you are saying about turning up the voltage. I do have a chinese led psu, and I tuned it to 12v. The thing is, a while ago my voltage regulator on my arduino blew up because of an affaire involving the endstops (I bet you can guess what happened ;) ), and I ended up installing a mosfet used in this tutorial: [hassanulmakers.wordpress.com].
Now that you said it, I´m tempted to try to increase the voltage to 14v, and, I don´t know...maybe the new mosfet is up to the job?

Thanks!!]]> mato84 Reprappers Sun, 21 Feb 2016 14:48:29 -0500 https://reprap.org/forum/read.php?4,629591,629856#msg-629856 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629856#msg-629856
Insulating under the bed is worthwhile if you haven't already. You can also put a blanket on top of the bed during the initial heating.]]> dc42 Reprappers Sun, 21 Feb 2016 13:38:09 -0500 https://reprap.org/forum/read.php?4,629591,629845#msg-629845 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629845#msg-629845 the_digital_dentist Reprappers Sun, 21 Feb 2016 13:18:45 -0500 https://reprap.org/forum/read.php?4,629591,629840#msg-629840 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629840#msg-629840 mato84 Reprappers Sun, 21 Feb 2016 13:10:19 -0500 https://reprap.org/forum/read.php?4,629591,629837#msg-629837 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629837#msg-629837 mato84 Reprappers Sun, 21 Feb 2016 13:06:56 -0500 https://reprap.org/forum/read.php?4,629591,629600#msg-629600 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629600#msg-629600 dc42 Reprappers Sun, 21 Feb 2016 02:51:40 -0500 https://reprap.org/forum/read.php?4,629591,629597#msg-629597 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629597#msg-629597 o_lampe Reprappers Sun, 21 Feb 2016 02:35:31 -0500 https://reprap.org/forum/read.php?4,629591,629592#msg-629592 Re: 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629592#msg-629592 elwood127 Reprappers Sun, 21 Feb 2016 01:30:01 -0500 https://reprap.org/forum/read.php?4,629591,629591#msg-629591 12v/30 amp car relay+1n4148 diode? https://reprap.org/forum/read.php?4,629591,629591#msg-629591 I was thinking of speeding up my heatbed heating time and I read that a relay is the way to go. I happen to have a 12v 30a car relay and a 1n4148 diode in my spare box, and I wanted to use it as a flyback diode.
Btw, I have a ramps 1.4 and a 12v 30 amp psu.

Thanks a lot!!]]> mato84 Reprappers Sun, 21 Feb 2016 01:21:22 -0500