I figured I’d go fancy with not just a heated bed, but a DPDT relay powered heated bed (based on rumors of the RAMPS not quite being up to the amperage draw of a large bed.
So…since it’s a dual throw relay, should I wire in both positive and negative to the relay, or just switch positive?
Or switch positive, split in half across the relay terminals so there is less total load on each?
Why don’t you use a solid state relay? I’m using one for my 400 x 400 mm heated bed ( 1000W), and it’s working perfectly. AC powered.
Be prepared for a significant amount of chatter from the relay as the bed is cycled about the setpoint. You might find that annoying.
@Rien_Stouten is used automotive relays in the past…just sticking to what I know.
I take it a solid state relay would be silent?
@Mike_Miller totally silent.
@Mike_Miller And you can use PID, instead of bang-bang.
What is everyone using for large heaters, looking for about 400mm with the solid state relay
@Peter_L
I used a toaster iron.
My test shows I need to raise (lower?) the gauge of wire I’m using. Which is a pity…this was the lowest gage Rat Shack carried.
Confirmed Ramps not up to the task, had to replace fuses on two of them… But the one on the 12x12" bed works fine post repair. Curious, what power supply are you using?
Lower gauge = thicker wire, if I recall correctly
Yup. I’m just wondering what a suitable gage should be. I requested 50c and it did that okay. I requested 100c and it seemed to have difficulty rising above about 60c and the wire going to the heater was getting much warmer than I felt comfortable with.
@Peter_L silicon heating pad from alirubber on aliexpress. For 400mm x 400mm bed go 120v w/ SSR, and around 500w. I have a similar size bed, and wish I went mains and higher watts. My bed is 400w @ 24v. It maintains heat fine. But abs 110c heatup is longer than I’d like. Get a 1/8" aluminum heat spreader for between the heated pad and the glass. This aluminum also gives you somewhere for the bed leveling screws also.
@Eclsnowman did you tell them what size and wattage/voltage you needed or was this something already designed?
@ThantiK I spec’d it myself. Tell them the size, wattage, voltage, leads length, any holes you require. I also had them install dual thermisters in case one ever died since its encapsulated in the silicone and tough to replace. Costs $25 + shipping. I chose dhl and had the custom bed in 6 days from order. Daisy is great to deal with: daisyhuang (at) http://alirubber.com.cn
@Eclsnowman , they’ll put holes in it for you? Didn’t know that! Very interesting!
@ThantiK they will do holes, zoned heating, etc. Just give them the spec. They make lots of industrial heater configurations for tons of companies and equipment.