So, I’ve finally decided to make about 10 of these FET switches.

I’ve finally understood of how this works, but one thing is still unclear to me:
Is it possible to use a super capacitor with a very high value resistor to prevent overcharging to the cap?

It’s the only component that I’m unsure if I should actually order.

Super caps are usually too big to fit tail switch assembly!

This one is the exact same size as the battery lonoceans linked though, which is very nice :D:
https://www.mouser.ca/ProductDetail/Seiko-Instruments-Micro-Energy/XH414...

And it can actually be shipped to any country, unlike a lithium-ion cell

BlueSwordM wrote:

So, I’ve finally decided to make about 10 of these FET switches.

I’ve finally understood of how this works, but one thing is still unclear to me:
Is it possible to use a super capacitor with a very high value resistor to prevent overcharging to the cap?

It’s the only component that I’m unsure if I should actually order.

It looks like the capacitor is rated for 0.3 volts more than the battery and 50X the charge rate as well. It should be fine the way it is

The stored energy will be about 6% of the battery, might want to bump up the charging rate.

Is there a schematic somewhere? It would be nice to charge the capacitor to the full 3.3 volts if it doesn’t cause other problems.

Yes there is:
https://www.mouser.ca/datasheet/2/360/seiko_XH414HG-IV01E-1202874.pdf

WTF wrote:

It looks like the capacitor is rated for 0.3 volts more than the battery and 50X the charge rate as well. It should be fine the way it is

The stored energy will be about 6% of the battery, might want to bump up the charging rate.

Is there a schematic somewhere? It would be nice to charge the capacitor to the full 3.3 volts if it doesn’t cause other problems.

According to post 24 it is being charged to 3.3 volts and the charging is limited with a 2.2k resistor in series with a diode, looks like changing
the charging rate is pretty easy.

The spec sheet for the battery says it has “continued stable capacity characteristics even after the battery is overdischarged down to 0.0V. “
So maybe its possible to drain the battery to keep it from shorting out and destroying itself while its being installed.

Ok then.

I’ll be ordering the PCBs first, then the components.

Which PCB is the best, or rather, the most appropriate?

I’m quite bad around PCB design, so I don’t know if the Rev B is the most appropriate, or what shiczobovine did.

If your going for the lighted indicator fet switch then rev.B has a lot lower quiescent current. I think loneoceans also added a second fet pad in the middle of the spring in rev.B. Are you building fet switch with the indicator or just the fet switch?

Just the FET switch. I like lighted tailswitches, but I don’t want to do additional work.

I just want to build 2 FET switches for me, and sell the remaining 10 to people who can’t, or don’t want to build these amazing switches.

So, would the Rev B be the best bet?

I’m ready to order the PCBs, but not the components yet.

I’m probably going to sell the rest with my dual BeCu springs so other people can enjoy it.

If shiczobovine’s design uses the same components, I would just order both, 3 of each and wait to see which one works better. Then order more of the design you like. Seems like people are having problems getting the battery installed and your going for the super capacitor. Seems experimental.

Oh now I’ve noticed there’s a place for a linear regulator on the board…

Silly me thought the cell/supercap was directly connected to the battery supply. Now the wait begins since I’ve placed an ordered for 12x boards.

I’m going to order some of these in a few days. I was hoping the bugs might get worked out before I did.
Which boards did you go with blue?

I’m going to order 12 of Rev B, since I prefer the LFPAK33 footprint.

Still haven’t confirmed the payment though.

Do you think I should order 6 of each just to be safe?

Do you think I should go for the 1Oz option, or thicker 2Oz copper option?

Sorry. It’s my 2nd time ordering a PCB.

You can use either one. He describes it back in his first post under the 16mm oshpark link. It’s also in the descripition at oshpark.
If you are using the LFPAK33 that is.

Oh no problem then.

Will order the boards right away. Was confused with the Q2 option in the Rev B and the Q1 option in the Rev S, but they are of the same footprint

Nice, thank you again!

Let us know how it goes Blue. I’m going to wait and see how your’s goes before I order any. I like the super capacitor idea.
I’m pretty sure you already know about Arrow’s free shipping. I order everything I can from them. Thought I mention it anyway.

Yep.

The bigger problem is that only Mouser can distribute the super cap…

So I’m going to have to order about a hundred SST-20s to get free shipping.

My GFS16’s PCBs have finally shipped!

They should be coming next week or two weeks after that.

I’ll also be ordering the components soon. Since I’ll be building about 12 of them, there will be 10 remaining.

I’ll be including a dual BeCu springs, a small and a large one.

Who wants in, if I actually manage to build any?

1. BlueSwordM

2. BlueSwordM

3. Inkidu

4. Shirnask

I’ll take one

Shirnask and Inkidu have been added to the list.

Very interested - I'll take 2, saves me the trouble for sure  Thanx!

I don’t think many people were reading along in this thread or they would have jumped all over Blue’s offer for the loneoceans fet switch with spring.

I’ll take 2 please, and thanks!

Never said free. Will probably sell it at cost, with shipping. It does cost money to actually make it.

It should be fairly easy to build.

moderator007 wrote:

I don't think many people were reading along in this thread or they would have jumped all over Blue's offer of a free loneoceans fet switch with spring.

Shhhh! 

No prob there Blue!

1. BlueSwordM

2. BlueSwordM

3. Inkidu

4. Shirnask

5. TomE

6. TomE

7. Kawiboy1428

8. Kawiboy1428

BTW, I’m probably going to include the springs inside of the package if you don’t want/need a bypass, although not soldered for shipping not to explode.

A dual spring setup will easily be able to sustain 20A continuously.
Technically, it’s 21A for nickel plated, and 24A for silver plated, but it’s about the same number for me.

Blue, which super cap did you go with, if you don’t mind me asking.
I ordered 6 sets of oshpark boards.

BlueSwordM wrote:

Never said free. Will probably sell it at cost, with shipping. It does cost money to actually make it.

It should be fairly easy to build.

I haven’t ordered the super caps yet, but:
https://www.mouser.ca/ProductDetail/Seiko-Instruments-Micro-Energy/XH414...

If you want, to lower costs, I can buy in bulk the components with you. Will ship them as quickly as possible.

BlueSwordM wrote:

1. BlueSwordM

2. BlueSwordM

3. Inkidu

4. Shirnask

5. TomE

6. TomE

7. Kawiboy1428

8. Kawiboy1428

BTW, I’m probably going to include the springs inside of the package if you don’t want/need a bypass, although not soldered for shipping not to explode.

A dual spring setup will easily be able to sustain 20A continuously.
Technically, it’s 21A for nickel plated, and 24A for silver plated, but it’s about the same number for me.