Go Down

Topic: Single digit, Seven segment Numitron program and pcb design needed. (Read 8573 times) previous topic - next topic

Daddyfredregill

I guess i am a liitle confused then. This will all be in watch form. So i cant unplug the batteries all the time. So what will happen when it is being run by batteries then I plug it in to charge it? Will it get twice the voltage? I thought it had to have that circuite in there just like a cell phone when you plug and unplug it. Sorry i just dont understand.

Again thanks for being patient.

wvmarle

Just unplug them to charge them, then reconnect the batteries. Or if you have a second battery pack, swap it out. One to the charger, the other on the watch.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

I plan on majing this watch solid brass and once it is pit together batteries wont be very easily excessible.That would work but i plan on this being like a cellphone. I dont want to have to swap batteries.

wvmarle

So the batteries would go inside the same compartment then as well.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.


wvmarle

That has some serious consequences for the design, as the battery holder will be on the PCB. So the final design depends on the size/shape of the battery and it's holder.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

Yes the battery shape is important, the watch itself i will be able to machine to any shape of pcb and battery as long as it is small.

Daddyfredregill

I will probably use the same size battery in the original post link on hakaday. Looks like the battery was from sparkfun. 110mah 25 by 15 mm. The pcb can be bigger than the battery by a little though.

wvmarle

the only battery I see in that post is a 400 mAh Li-ion battery sitting next to the PCB.
If the battery is fixed, there's no real need for a supercap either. It doesn't add much time for your timekeeping if you run out of battery (and the RTC can do with as little as 1.3V or so, when your processor stopped working already - maybe even the boost converter). Can connect the battery backup pin directly to the main battery.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

I saw the 110mah battery in the pdf in the charging cicuit.

Daddyfredregill

In the parts list he shows both 110mah and 400. So i dont know what he is using.

wvmarle

I found this battery at Adafruit. Comfortable fit under the display.
A bit bigger capacity has this battery which would fit next to the display, broad side, making for an overall PCB size of 20x40 mm, and an overall thickness of about 15 mm.

The battery will cut off at 3V so a supercap would still come in useful to keep the time as the battery recharges.

Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

This battery is from adafruit as well. It is more square but would sit under pcb as well.


wvmarle

That's the second one I linked to.

For the overall arrangement: the surface area needed for the components excluding supercap, battery, connectors and push buttons is a little more than the surface area of the display itself. Without battery, I had the supercap, buttons and display on one side of the PCB, the rest on the back - partly in between the pins of the display.
The various through-hole components (the display itself, the supercap) do severely limit how things can be arranged, though.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Go Up