Ok do you guys have SSR recommendations? I really need to get printing abs on this thing. This SSR lasted about 20 minutes through the PID autotune. Im running the 12x12 QU-BD silicone bed with a 12v 30amp power supply.
Had a heat sink, thermal paste and a fan. IDK what to do now…
A FET should do the job, discussed here:
https://plus.google.com/116889746506579771100/posts/LSbYSeGueyH
I have had terrible luck with SSRs.
A Fet won’t work since I assume you are switching AC.
I am swtiching 12v DC. Id like to stick to ssr’s purely for the simplicity of hookup. The heatsink on this one was the recommended sink for the relay. Im not sure what happened here
If you were switching AC that would definitely melt, as it quite clearly states only 60V DC!
Oh, DC? Then I’ve had pretty good luck. Maybe get a Zener on there. What is the duty cycle and period? You could use a mechanical relay if it’s slow
Enough.
Seriously, use a FET, PID duty cycle is something like 10-20hz, that will kill a mechanical relay eventually. All other Pwm stuff on the boards is handled by FETs, the on board one just isn’t rated high enough. The thread I posted includes some diagrams and instructions from folks more knowledgeable than I on how to do this.
Finn sloss is right on the money. Wrong SSR.
@Finn_Sloss and @Rien_Stouten Im switching 12v DC. No AC in the line. That SSR was well within the specifications for what I am doing
This SSR only supports up to 25 amps load. it works fine with MK2B which i m using now. i have the same SSR and heatsink. You need to get one that can support more than 30Amps load such as Amico 40DD. The higher the better for your case.
Dude your going to have a fire using speaker wire that is rated 10 amps, that maybe some your your problem, add a fan.
Does your load draw 30 amps?
@Jean_Beauregard The wire Im running is 12ga speaker wire. Its the same wire I ran 1000w subwoofers from back in my car audio competition days. It doesnt even get warm in this application. Do you have a recommendation for better wire?
On QU-BDs page they list that the bed “can” pull 20 amps. There is no limiting or anything that I can see so I’m guessing it pulled everything the power supply could give (rated for 30A) since it was the only thing hooked up.
Thanks for the recommendation @Melvin_Chen and @Tim_Rastall I like the idea of a FET but the hookup of and SSR is so easy.
@Tim_Rastall Do you have a copy of the diagram you mentioned? The dropbox link in the thread is dead.
@Joe_Spanier , measure the resistance across the bed. The maximum current is I=V/R. The current can’t get any higher than that, regardless of the output of the power supply. The only way to increase the current on that bed is to increase the voltage. The resistance would have to be .4 ohm or less in order for it to run at 30 amps.
I have another theory. I’m not a EE, so this is just a dangerous guess. I remember speaking with some EEs at work, and I believe @Thomas_Sanladerer also mentioned that operating a transistor in an under voltage state, could lead it to operate at a higher resistance. I’ve noticed that my SSR that is the same brand doesn’t trip well with 5VDC control signal, but it trips fine with 12VDC.
Anyhow, good luck
Here is the opto zz there is 45 amp rated in there, speaker wire is a poor choice because of the heat rating. Here is the link
http://www.opto22.com/site/pr_selector.aspx?cid=4&qs=1006#1016
i have to say that some SSR look like they handle the load on paper, but some of them are made in CHINA, and they dont work like they say on paper. judging from the way its melted, looks like the heat inside didnt go to the heatsink. it will be interesting if you can throw an ammeter there and know for sure how many amps you draw, for me, i will 2x or even 3x the rating. 60A relay? 60A mosfet? anything made in CHINA i will derate it 2x, so that SSR of yours is prolly safe for 10A.
Was safe for 10amp, was lol
yea was lol. i did use some of these CHINA type SSR. i have them switching my soldering iron to control temperature. and indeed it was really easy to hook them up. I intended them to be used for a geeky bath water temp control … somehow i didnt trust it that much.
