USA Cal Club: Round 2

[cellularmitosis]

Nice job!  What resistor values did you decide to use?

[ArthurDent]

The resistors I used for the most part were Vishay RNC90Z 2ppm tempco and bought surplus at a low price. I used 988R instead of 1K, 12K931 instead of 13K, 68K000 instead of 70K, whatever available values were close and I figured would work after reading a lot of post about choosing resistor values. The 10 volt adjustment pot is a 5K WW 30 turn miniature one with 2K5 in series and that combination is across an 88R68 ohm WW resistor. The pot and the 2K5 resistor are the only two precision resistors that aren’t really low tempco but where they are in parallel with the very low value 88R68 ohm resistor their effect isn’t that great.

The metal boxes I used that the Dr. Frank boards fit perfectly into were a couple I got with Motorola GPS boards where I needed the boards at the time and the boxes went into, let’s say, my ‘stock’ pile so they are an item that isn’t really available. Inside the steel box is a thin sheet of fiberglass board for insulation and the box is mounted on a piece of brown phenolic board which is mounted in the case.  The case is from a scrapped HP bus extender and I got two of them for cheap just for the case and the power connector.

[AG7CK]

... The battery supply and charger are built into the case I'm using. No switches were used and just A.C. in, red/green bi-color LED for charging/charged and live indication ...

Very nice box.

Is the charger 110v in? Is it linear or switch mode? Does it charge 4S 18650 Li-ion (ca. 14.8v) which feeds the 12v-regulator for the ref? And you just added wires to the PCB in the plastic box for external LED indicators (charging/full)?

Do you (or Does anyone) know about an ebay-orderable plug-n-play linear charger for 4S batteries?

[ArthurDent]

The charger I used is a 100-240VAC switcher designed for 4S1P 18650s and the four battery 4S1P holder has built-in protection circuitry. I removed the A.C. pins for the charger plug and mounted the plastic charger case inside the metal case everything is built into. I brought the A.C. leads out to connect through a back panel fuse holder to the line filter/IEC connector. I also brought the 3 leads for the red/green LED out and mounted the LED on the front panel. The charger LED is designed to show red when charging then green when it switches over at 95% charge and trickle CV charges at 16.8VDC. The green indication will then stay on until the battery voltage drops whether the charger is plugged in or not.

The protection circuit in the battery holder will disconnect the batteries from the load when the voltage drops below a certain point so the batteries can never be run flat and the green LED goes out at this point as well. The battery holder output and charger output are connected to the 7812 regulator I used because I have a buffered 10 volt output and that 12VDC gave me some headroom. I'm not concerned about using a switcher instead of a linear charger because I never plan to use the reference while it is plugged in and charging, so the type of charger makes no difference to me. Using the reference while it is plugged in could cause some offsets or noise in the output voltage due to capacitive coupling or whatever so I'm avoiding those problems by only using the reference on battery power.

[hwj-d]

Someone know, what happens to Jason?
Now 2 weeks ago, I sent him a pm, no reaction. 

[cellularmitosis]

Oops, I must have missed that one, sorry!

[Inverted18650]

I am officially submitting my request to join the CAL Club. I am very close to completing my 'mini CAL lab' in my home office and I am ready to take the next step.

[bitseeker]

Welcome aboard! The conductor (cellularmitosis) will be by to punch your ticket.

[ArthurDent]

Inverted18650 - "I am officially submitting my request to join the CAL Club. I am very close to completing my 'mini CAL lab' in my home office and I am ready to take the next step."

That sounds like your introduction into a support group. 
 
You are among kindred spirits.

[cellularmitosis]

Glad to have you on board!  Can you send me a direct message with your shipping address?

[Inverted18650]

Hello everyone, my name is Chris, and I am a volt-oholic. I usually have my first glance at the DMM's shortly after waking up and again right after breakfast. Sometimes I try to hide my addiction from others, but feel like this may be a good place to share my stories of obsession.

[cellularmitosis]

Oops, the ref arrived last week and was being held at the front office.  I’ll get it measured tonight and send it on it’s way!

[hwj-d]

May I ask again very carefully if the USA Cal Club idea continues? Jason was last seen more than a month ago and actually wanted to send the ref to me.

[bitseeker]

Well, let's see where we are. In August of 2018, nikonoid had the ref. Then, Svgeesus got his turn in November. Next, would've been dr.diesel, but he requested to take his turn in or after Spring 2019. Then Vacuuminded got it in December when hwj-d missed CM's message. So, hwj-d would be next.

The remainder of the list for this round, after hwj-d, is as follows:

flittle
bitseeker
orin
GEOelectronics
rhb
RandallMcRee
ArthurDent
edavid
CalMachine
Conrad Hoffman
VintageNut
vindoline
technogeeky
TWMIV
Muxr
SirAlucard
MaxFrister
CatalinaWOW

Since it's almost Spring, dr.diesel will need to get re-inserted sometime soon-ish.

I sent CM a PM.

[hwj-d]

Yes, i missed it shortly half a day, because i didn't see that dr.diesel postponed his appointment, in timely manner. In the meantime, however, this has been clarified with the order up to me for quite some time. Actually Dr. Diesel would have to line up again after me.

[cellularmitosis]

Sorry guys, I am flying back into town tomorrow.  I had it packaged up and had intended to ship it before I left town but I didn't.  I'll get it shipped out Monday morning.

I've been neglecting this venture  .  I don't like that reality but the truth is that my efforts have been focused elsewhere (I've been learning a new software platform for work, and I'm likely to be focusing on that for most of 2019).

Just putting out a feeler -- would anyone be interested in taking over the cal club?  I'd be happy to donate the reference to the cause 

[TiN]

Sounds like cellularmitosis found a cure for voltnuttery! Please do not share the recipe  .

[hwj-d]

Hi Jason,

I understand such time problems, didn't want to put you under pressure but only whether it goes on. It's a pity that you can't put your energy into this project so much anymore. But I'm pretty sure someone in the usa can be found to step in, or the list should become a self-runner by now.

All the best,
cu

 

[hwj-d]

Today, the ref reached me. 
Someone put 10$ into the package, thanks ...  ... no, i think that was actually meant for someone else who deserved it better.
A first look says, all ok. So i take a first measurement w/o detailed temp (more to ftp).
My 34461A is >100µV out now, so I take it with my DMM6500 wich is inside one year calibration.

[cellularmitosis]

Hehe, perhaps the $10 can become the calclub good luck charm

vindoline has graciously offered to take over the cal club.  Vindoline, would you like to start a new thread?

[bitseeker]

Thank you for taking the reins, Vindoline! And thank you, cellularmitosis, for pioneering our cal club.

[CatalinaWOW]

Thanks cellular for what you have done, and vindoline thanks for taking over.  Let us know how to help.

[vindoline]

Hi everyone, I don't see any need to start a new thread for this. I'm just here to help out cellularmitosis with the logistics of getting the reference moved around to the members. cellularmitosis has done an amazing job of setting the club up and getting things going. Thank you! Now take a well deserved break!

 My first goal is to get the reference(s) moving around quicker to the members. I think this will re-kindle the interest and enthusiasm of the group. I'm open to any ideas or suggestions. My initial thoughts are to "recommend" that we try to limit each visit of the reference to 2 weeks or less. I would reach out to the upcoming recipients to make sure they were ready to use their slot. If not, no problem. Life happens. I would just ask them where they would like to be placed in the queue. What does everyone think?

[bitseeker]

Sounds good to me. Let me know when you get a sense for the timing so we can coordinate with you and be ready.

[TiN]

I don't see any need to start a new thread for this.

I agree, no need to spread entities.

vindoline, I guess I need a shipping address for new 10V CalClub ref. Please send me PM with details (and phone # for EMS).
Have it ready to go in next week or so.