I dont mean to argue with kiss however to be specific a switch freq >20khz is true you wont hear that, however the same is true for <20hz!, the heater in my office runs at 50hz I never hear that.
Hi, I am working on a school project. I am looking towards building a heating jacket for winter (it gets really cold in Ottawa, Canada). I am doing this for my electronics class. Currently I am looking on having 3 heating elements that have roughly a maximum load of 10 V and 2 A each. I would like to use a dc-dc buck booster as a voltage regulator/voltage booster. It would impress my professor if I am able to digitally control the voltage with a micro controller. This is where I am struggling the most. I am hoping to digitally control a buck booster in order to change temperature.
Thank you
Finally, why are there two frequencies: Would one be in the micro controller and other in the MOSFETS?
Hi, some important design issues that come up with this kind of product..
All this help has been great. Thanks to you guys I am learning a lot!
Mr Al, I thought building this project was going to be much simpler. Thank you for helping me understand better what it takes to build this project. The only part that I have purchased are the heating elements, which are carbon fiber heating tapes from https://www.carbonheater.us/. I thought they would be great since they are flexible and soft. Using strips of 120 mm length 15 mm wide as a heating element (3V 1.5I would give 60 Celsius). I drew a schematic https://imgur.com/WZt95xH. I was thinking to add another group with two heating elements to warm the arms too! Yet, I did not include it in order to keep the circuit simple.
From what I understood, PWM is best when we match the supply to the load and a buck converter is also used. In the beginning I wanted to control each group of the circuit with a buck converter, but I found it hard to control the buck converters supplied on ebay digitally since they use a potentiometer.
When reading about the heating jackets in the market I see that they only had 3 settings for heating (low, medium, and high). I thought it would be awesome to show the professor that I can build one with an added feature of variable temperature (anything between low to high).
I appreciate your expert advice. I want to learn and all discussions we have here are very enlightening.
I mentioned PID control
Hi,
But why is there 4 ohms in that schematic when the others are 6 ohms?
Now the question is
Total power required is therefore 8 x 4.5W = 36W.8 heating elements at 3V 1.5A
Assuming you run the batteries completely flat (a bad idea) the energy available from the batteries is 7.4V x 6Ah = 44.4Wh.7.4V supply and 6000mAh
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