Yes.Are woried about human safety?
It would not be advisable to put the battery pack in contact with the human body for this exercise for three reasons:Yes.
I had thought about putting the battery on the inside of the vest. Battery loss will heat the human.The battery will be worm and work better than if the battery was at -40C, out side temperature. But batteries burn up some times. Do you want a battery pushed against your skin. On the news they showed some pictures of E-cigarettes catching on fire in a picket.
First thought was to power the MCU from the 3V to 4.1V (3.6V nominal) battery pack, the same as the heaters. I can't see a problem with this as far as the MCU is concerned but, as I said, the problem is driving the three MOSFETs with just 3V, but there are simple ways around that.How is the computer being powered?
Yeah, you could make the e-resitor control a constant current to give a linear relationship of R_total versus output voltage but, in this case, the MCU could sort all that out without any added hardware.40 yrs ago , I did the same with HP power supplies and used a DAC R ladder to control the level. In my case for immunity, I used isolated mercury wetted relays. Now there are better options. The digital pot has more resolution but limited range.
Normally a constant low current drives the pot to generate the control voltage.. But dont guess, test it
A suitable smoothing cap prevents glitches.. Twisted pair or short leads is important to reduce ingress.
Hi, I have read all your comments and I find them very helpful. Thanks a lot, I appreciate it!
I was brainstorming regarding the setup for the elements: 3 groups in parallel, and each group has elements in series (pictured attached). I thought this was a good idea so if a group fails, others can continue functioning. What do you guys think?
Also, how would the set up of the batteries affect the circuit? From what it is understood, batteries in series increase voltage and in parallel increases current. Would a having batteries in parallel and in series work too?
Regarding MOSFETs, I completely agree with you. MOSFETs will be implemented in design. How to know which MOSFET would work best? I am worried they might get too hot for safety.
Thanks a lot. You guys have been great. Your input is valued!
In my case for immunity, I used isolated mercury wetted relays.
.
I can specify a suitable MOSFET if you would like.
(1) All capacitors are through hole (not surface mount) ceramic X7R dielectric
DATA SHEETS
(1) PMOSFET
https://www.digikey.co.uk/product-d...age/TPH1R712MD,L1Q/TPH1R712MDL1QCT-ND/5323104
One quick question, are we using the capacitors as protection?
MOSFETs
spec
Just to make sure, in order for our chosen MOSFET to be active a voltage of 4.5 V should be supplied to its gate correct?
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