build a thermostat

[gophert]

That’s why I seem to be obsessed with voltage-dividers

Further proof that people tend to use the "tools" in their current toolbox to solve problems before searching for new tools. Some people know when (learn when) to search for new tools and some people end up trying to create crazy Rube Goldberg solutions with existing tools (or they grab a sledgehammer, to pound a finishing nail, a chainsaw to cut a dowel or a gun to solve an argument).

Cheers.

 

[AMIRAAM]

from all those people , i don't care about who hasn't the good tools , but i care about those who thinks that they are more intelligent
thank you a again
to another question goodby

 

[DrG]

from all those people , i don't care about who hasn't the good tools , but i care about those who thinks that they are more intelligent
thank you a again
to another question goodby

Where is you patience and understanding? Please go back and read this entire thread. People spending time and effort to understand you and help you and the first time you do not get a response that you like, you act insulted.

 

[AMIRAAM]

please what i mean that the people who think that they are more intelligent ,when they learn a little basics about informatique or about any another domaine ; they cant be patient and try directely to solve the problems of the other , that is all

 

[AMIRAAM]

I am okay with that

Further proof that people tend to use the "tools" in their current toolbox to solve problems before searching for new tools. Some people know when (learn when) to search for new tools and some people end up trying to create crazy Rube Goldberg solutions with existing tools (or they grab a sledgehammer, to pound a finishing nail, a chainsaw to cut a dowel or a gun to solve an argument).

 

[DrG]

please what i mean that the people who think that they are more intelligent ,when they learn a little basics about informatique or about any another domaine ; they cant be patient and try directely to solve the problems of the other , that is all

Ok, you seem like a reasonable person who is trying to learn and I believe I am as well.

I ask that you consider some points. This is the 26th post in the thread. You started by posting a schematic and saying you wanted to add capacitors and how and why can you do that.

I asked you where the schematic came from and you really did not answer - simply saying that there are a lot of them on google, or words to that effect. But, I tried to answer the question and described the circuit.

Then it was add or remove capacitors....

Then it was LEDs...

Then it was resistor dividers..

and so on.

Never, have you said - "I am building an incubator. I want to use this schematic but I am having trouble with this or that part".

People try to help you even though you are doing a very poor job of explaining yourself. You must learn to accept that not all of the responses are going to suit your mood.

That is my point.

 

[AMIRAAM]

please i am very sorry
that may be because I'm not used to forums
please again i am sorry

 

[DrG]

please i am very sorry
that may be because I'm not used to forums
please again i am sorry

ok no problem.

 

[gophert]

please i am very sorry
that may be because I'm not used to forums
please again i am sorry

Instead of being sorry, answer the questions!

 

[ChrisP58]

but please another small question :
why the voltage divider is not good way : ( i will keep the PNP)


View attachment 122471

Voltage divider?
In this circuit, R6 and R8 do not really form a voltage divider.
- R6 is there to control the base current of Q1.
- R8 is there to turn Q1 off when the output of the LM339 goes open.

The voltage across R8 is clamped by the base-emitter junction of Q1 and will never be more than about 0.7 Volts. If they formed a true voltage divider, then the voltage across R8 would be 10.9 Volts when the output of the LM339 was low. (Assuming Vcc=12V and there are no other currents in or out of the junction)