892
edits
Difference between revisions of "Open Biotech/PCR"
Jump to navigation
Jump to search
→Peltier
Hbergeronx (talk | contribs) |
|||
| Line 230: | Line 230: | ||
I've been looking at the specs of some Peltier chips (see https://docs.google.com/file/d/1u2m--LONYCOyvcp76spoAP3wN3nWroROwfTtoJx9TpeeeMYY1WVNb1-KCXOk/edit?usp=sharing ) and on some of them, they seem to be designed for lower temperature operation and the lifetime of the device will be significantly reduced if you operate them at a high temperature (the limits of the device in the attached spec device, for example, is 80C.) At 95C, the hot side quickly ramps up from the cold side temp, which is starting at 95C, I've heard as much as 4x the rate of the cold side. By the time you got to 80C on the cold side, you could easily exceed 150C if your heat sink isn't able to pump that much heat that quickly. | I've been looking at the specs of some Peltier chips (see https://docs.google.com/file/d/1u2m--LONYCOyvcp76spoAP3wN3nWroROwfTtoJx9TpeeeMYY1WVNb1-KCXOk/edit?usp=sharing ) and on some of them, they seem to be designed for lower temperature operation and the lifetime of the device will be significantly reduced if you operate them at a high temperature (the limits of the device in the attached spec device, for example, is 80C.) At 95C, the hot side quickly ramps up from the cold side temp, which is starting at 95C, I've heard as much as 4x the rate of the cold side. By the time you got to 80C on the cold side, you could easily exceed 150C if your heat sink isn't able to pump that much heat that quickly. | ||
I think to ensure against damage or reduced life, you have to carefully control the amount of volatge/current applied. A feedback loop to limit applied voltage based on temp of hot side seems to be a sensible addition. I'm still trying to figure this out for a temperature controlled minielectrophoresis unit that I am designing (to be open source). A cheap unit becomes not so cheap if after a handful of runs, you have to fix it: not trying to imply that you haven't thought of this or to be a downer, but just raising awareness of something that only recently came to my attention. | I think to ensure against damage or reduced life, you have to carefully control the amount of volatge/current applied. A feedback loop to limit applied voltage based on temp of hot side seems to be a sensible addition. I'm still trying to figure this out for a temperature controlled minielectrophoresis unit that I am designing (to be open source). | ||
:Yeah. The temperature sensor + MOSFET + microcontroller allows us this dynamic control :-) (also, please put three tilde characters to tag comments with your name) - [[User:Juul|Juul]] ([[User talk:Juul|talk]]) | |||
A cheap unit becomes not so cheap if after a handful of runs, you have to fix it: not trying to imply that you haven't thought of this or to be a downer, but just raising awareness of something that only recently came to my attention. | |||
== MOSFETs == | == MOSFETs == | ||