I'm building a pcr thermal cycler (DIY), does anybody know if a 0,5ºC ramp rate is acceptable ?

The ramping rate gradient another option with an temperature variability of 0.1 will be best. The effect on the amplicon, as discussed above, can be more pronounced as above scenario. Its effects will be more visible were annealing temperatures and 94 C difference is larger and slow ramping probably will overcome the point raised by Sarfraz Kiani. On the other hand higher temperatures will effects polymerization rate thermostable polymerases. So I will go for a function of gradient ramping of 5 C to ensure my annealing is maximum. This will, I am definite, also rewrite out amplification equation after its analysis.
Ahsan

5°C ramp rate is very good for PCR and will be time saving. Please go ahead

Taq polymerase is very efficient. As soon as it gets ample temperature it will start its activity between 67 - 74oC. As temp. ramp speed is slow, Taq would get enough time to amplify the DNA. Therefore, you'll get lots of unwanted small DNA bands along with primer dimers. Think about these aspects in depth. If increasing ramp speed costs you a little higher then go for it, spend more to increase ramp speed as higher as you can afford.

Dear Colleague,
It looks like this instrument might work but it will be slower. For example going from 94deg C (melting) to 55deg C (typical annealing) would take (94-55)X0.5=19.5 seconds and then from 55 to 72 (typical extension) another (72-55)X0.5=8.5seconds. You have not even started any of the ACTUAL steps, melting, annealing, extension and have already waited 19.5+8.5=28seconds per cycle (so about 19 more minutes per a typical 40 cycle PCR). It will slow experimental progress down. Without looking at your experimental design it is hard to say if it will negatively impact the outcome. It should not in my judgment. At times you want slower ramping on purpose (e.g. PCR with degenerate primers). But again only the actual experiment can verify this hypothesis. There may be a chance of side effects such as primer dimer or non-specific amplification. You can fight these "side effects" if they appear by simply adjusting actual hold times.
By the way. It may seem like ancient history now, but before first thermocyclers were introduced, PCR reactions were carried out using three water baths set at their respective melt, anneal and extend temperatures. Of course a researcher had to be present at all times, look at the stopwatch at manually move tubes and racks around. I have been lucky enough to always have access to good PCR machines, but if I were to risk loosing my experiment to an untested unit with undefined ramp rate I would probably try "manual PCR" instead.

Dear Colleague,
We could think that the faster is the ramp rate, the best would be a PCR. It's not as simple as this (see below).
As said by precedent colleagues, the ramp rate can range from 0.1 to 20°C/sec, and performances differ if it's for increase/warming (resistant effect) , more easy to peform from cooling for decrease temperature (Pelletier effect).
To be slower can increase PCR efficiency, but favour ie dimer primer formation.
And important also when the apparatus is very fast is the time which is necessary to stabilized the medium temperature after increasing or decreasing temperature (more instable according to metal or over composition of the blocks or capillaries).
So, to my mind it's an equilibrium between all these factors.
Best regards
Didier JAMBOU

Thank you everibody !
I'm at the initial stage of my research, but i think that the price will get higher as the speed increase.

Is it difficult for you to increase ramp speed at least 1 or 2oC/sec??? If you can increase the speed, then do it. Why you want to compromise even if it is for small research scale???

Hi,
I agree with Xiao-Dong on this. It is quiet good enough for biology teaching as you have stated the thermal cycler with 0.5 C but will actually take more time for amplification.

As I know, commercialised PCR instruments usually allow you to adjust the ramping speed between 0.5-3.0ºC/s, and in some new types between 0.1-20.0ºC/s. In terms of amplification success solely, 0.5ºC/s will definitely work well. The only problem is the running will be very slow.

The default ramping speed is usually 3-4ºC/s, but in some quick-running machines they use 10-20ºC/s, which doesn't work well with certain target DNA loci.

Hi!
For teaching purposes it is may be a good variant if the price will be very low, however for experiments it is not acceptable.