# \#4710 safety valve **URL:** \ **Category:** KOSMO MODULES\ **Created:** [January 26, 2021, 11:52am UTC](https://lookmumnocomputer.discourse.group/t/4710-safety-valve/2789 "2021-01-26T11:52:21Z")\ **Posts on this page:** 1\ **Showing post:** 149
**Author:** ![Caustic](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/caustic/32/15588_2.png) [@Caustic](https://lookmumnocomputer.discourse.group/u/Caustic)\ **Post date:** [May 2, 2021, 7:46pm UTC](https://lookmumnocomputer.discourse.group/t/4710-safety-valve/2789/149 "2021-05-02T19:46:31Z")
> [@Safety Valve - 27R is smokin' hot](https://lookmumnocomputer.discourse.group/t/safety-valve-27r-is-smokin-hot/748/2): > > From a quick peek at [the schematics](https://www.lookmumnocomputer.com/the-safety-valve), it’s in series with the heater filament which is speced as max 150 mA at 12.6 V so simplifying a bit total series resistance is 27 + 12.6/0.15 = 111 ohms which corresponds to 12/111 = 108 mA through the circuit from the −12 V rail, and the 27 ohm sees 27×(12/111)^2 = 0.32 W which is above the specs for a 1/4 W resistor. It’ll probably survive (the watt limits are set for a high ambient temperature) but it’ll be hot. You could replace it with a 1/2 W or 2-4 l… @fredrik suggests that the 27r should be more than a 1/4 w resistor. So either a 1/2W or you can put a few resistors in series. --- _[View the full topic](https://lookmumnocomputer.discourse.group/t/4710-safety-valve/2789)._