# Bed Heater Control Circuit & Software
**URL:** https://forum.lulzbot.com/t/bed-heater-control-circuit-software/22351
**Category:** Hardware
**Created:** [September 21, 2020, 2:21am UTC](https://forum.lulzbot.com/t/bed-heater-control-circuit-software/22351 "2020-09-21T02:21:49Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@biomurph](https://forum.lulzbot.com/u/biomurph)
#### Post date: [September 21, 2020, 2:21am UTC](https://forum.lulzbot.com/t/bed-heater-control-circuit-software/22351/1 "2020-09-21T02:21:49Z")
I’m working on a project that needs a ‘pretty accurate’ heated panel, and so the first thing I thought of is the TAZ 6 print bed. I’ve dug around on the Lulzbot site and found some reference. The best thing I came up with is [this pdf](http://devel.lulzbot.com/retail_parts/LulzBot_TAZ_Etched_Modular_Print_Bed_Heater_KT-HB0014/Taz_modular_bed_etched_AS-HB0006.pdf). It gives me the power requirement for the heater, and a part number for the Honeywell thermistor, but I am looking for more details on the rest of the circuit for the sensor and how to calibrate it. Honeywell has [this page](https://sensing.honeywell.com/135-104LAG-J01-thermistors) for it, and I’m familiar with Wein Bridge circuits but it would be nice to see how you folks are doing it and how to scale the sensor readings.
Also, I plan on using a PWM on the heater element with an off-the-shelf 24V/15A capable supply, thinking that a properly rated SSR will do the trick, but would like to see the circuit that you’re using. Is there a directory or repo that you could point me to?
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### Author:  [@JasonT](https://forum.lulzbot.com/u/JasonT)
#### Post date: [September 21, 2020, 8:09pm UTC](https://forum.lulzbot.com/t/bed-heater-control-circuit-software/22351/2 "2020-09-21T20:09:17Z")
I believe the Taz6 uses the Rambo v1.4 like the workhose. The schematic can be found in the link below. The board files are Altium but the board itself is a real basic Arduino derivative.
> **[Rambo v1.4 - RepRap](https://www.reprap.org/wiki/Rambo_v1.4)**
If temperature uniformity and accuracy is important across the build plate then you may want to pick up a FLIR camera and some thermal paste. I had an issue with one of the corners being colder than the rest. I’m waiting for a new toolhead before I do the experiment.
Depending on the magnitude of the desired accuracy a TEC might be a better option. They’re pretty easy to get down to a stable +/- 0.01C.