PBW needed

If you are talking about the DCS-RC Watchdog Generators I might be able to help you out in a couple of weeks. My email is in my profile.

rtr12 posted:

If you are talking about the DCS-RC Watchdog Generators I might be able to help you out in a couple of weeks.

I've lost track of where "we" are on the PBW.  Are you gathering raw boards and parts for GRJ's trimpot version? 

Will these be assembled or just a kit with bare PCB and a bag of parts?

For reference, was the Bill-of-Materials (e.g., DigiKey parts list) posted for the trimpot version along with the OSHPark link for anyone to order boards?  It's just that even if assembled boards are offered, the user must still solder the 3-pin square-pin header/socket to their DCSRC.  I haven't checked but I'd think MTH might have discontinued the DCSRC (???) if they are offering the Explorer in "Starter" sets.  So curious is anyone has considered offering a ready-to-go PBW that doesn't require soldering.  

We were actually considering a 555 based version that requires no adjustment, PnP.  It's probably what we should have done before, but better late than never.

Well.  I'm all for PnP but doesn't this still require the user to solder the 3-pin header (or socket) to the DCSRC?

Also, one reason for using the 74HC14 (vs. 555) was the drastically lower current requirement since no information is available on how much power can be "stolen" from the DCSRC to power this add-on.  I suppose one could use the CMOS LMC555 rather than the bi-polar LM555.

So that's why I was asking what the latest thinking is wrt the PBW.  I'd have to hunt it down but I seem to recall an OGR thread where I suggested a $5 cycling timer-module that would perpetually cycle power to a stock (unmodified) DCSRC on for 1 sec, off for 0.1 sec which means the DCSRC would not need to be opened and modified at all.  Problem was this was accompanied by relay clicking which could drive one nuts.  I don't recall what happened but perhaps a ~$1 eBay SSR (solid-state-relay) module could be paired with some kind of timer-module for click-less operation.

Stan, soldering the header to the DCS-RC doesn't require calibration, but tweaking the pot does.  The most questions I ever got were how to accurately adjust the pot without a counter or 'scope. 

I was thinking of the TI CMOS TLC555CP version, it has very low power consumption, easily drives the reset line, and makes the package calibration-free.  Quantity one from Digikey is 84 cents, so the price is reasonable.  Exclusive of the PCB, the parts for this should only cost a couple of bucks from distribution, so the parts cost is not really an issue.  I'd rather spend an extra buck on parts and have a board that can just be simply assembled and is ready to function.

Stan,

I had 2 extra PBWs that someone wanted. My originals from GRJ (the extras) went to the person in need. I wanted to keep one for backup, but was now sitting here with none left. Since I needed to make another one, I got with GRJ about offering some PBWs as kits, he was out of PCBs and parts. He brought up the 'no calibration needed' suggestion and went back to your idea from the original PBW thread mentioning the 555 timer idea and a PBW needing no calibration. I was using a different 555 here for testing, he mentioned your concern for too much power draw...and here we are. So far it is working pretty good on a breadboard (I ran my findings by GRJ and I think he was also satisfied). 

I'm in the process of getting some PCBs and parts for these and was hoping to offer them as unassembled kits. I was going to try this with PCBs and parts for only 10 kits. They are the ones GRJ posted above with the 555 timer, no adjustments needed. The parts I ordered include the 3 pin header that still needs to be soldered to the DCS-RC board. I would prefer offering kits, but suppose I could offer assembled units for those that are really opposed to soldering, but as you say the 3 pin header would still need to be soldered. 

As you point out with the Wifi Explorer, the DCS-RC has most likely been discontinued so demand could be quite low here. With that in mind I imagine there are probably still a ton of the DCS-RC sets out there in need of something to do. Perfect for conversion to PBWs.

I think the no soldering version you mention might also be worthwhile for those that do not want to even think about soldering something. If you could link me to the thread where this is described, I'll see about maybe putting together a few kits of that variety to offer along with the PBWs and see how it goes with those as well. Not sure if these are the proper type, but I have a couple of solid state relays around here somewhere. They are similar to the small ebay modules with the 10amp electro-mechanical relays that have become popular around here.  

I'm not too good at designing this stuff, but I am becoming somewhat proficient as a shipping and receiving clerk. I also kinda like doing this stuff, makes me feel like I am occasionally helping out here and there. So, IMO, adding the 'no soldering required' kit would be a bonus.

It would be cool if there was a 3-pin socket that would press into the PCB and make a secure connection.  Hard to believe something like that doesn't exist, I just couldn't find one.   If that were available, a truly "no solder" option would be available.

Actually, as it turns out, there is a press-in connector for .1" spacing.  Mill-Max 801-43-003-61-001000.  Not exactly cheap, but it does eliminate the soldering. 

Pretty cool, that was a good find!  But, I just put in an order at Digikey earlier today. Price wasn't all that bad, after all it is gold plated.  I'll add a few to the next shopping cart, just to see what they are like. I probably forgot something so I'm sure another order will be needed to finish something.  

I bet that price wouldn't deter someone that was opposed to soldering or would have to buy all the stuff to solder with for that one 3 pin header. 

There may be others, I just found that one first in a search at Digikey.

I'll try looking around for more possibilities. I was looking at this in Digikey when adding to my new order and it is a 'Value Added Item' and went on to explain they make them up when ordered. Still indicated you could get same day shipping though. That's a new one on me. Interesting!

Let's see now, what else can I add to that order to make it worthwhile and hurry things up?

I didn't even notice that it was labeled as such, I never ordered a "value added item" before from them.  Apparently, they chop a long strip of these up to make the size you order, interesting.  I was just looking for the capability and the proper spacing.

I just did some more searching and there seem to only be 3 in a 3 pin configuration. Here's what I found. They show up as 'Press Fit, Solder'. Guess I'll look at the data sheet a little closer. They are staying on the order regardless, curiosity has the better of me now.

They had many more listed with different pin counts. Just change the search results from the link and they should show up, I think. It worked, just uncheck the box for 'Number of Positions'.

Did you confirm the finished (plated) holes on the DCSRC board itself are 0.040" per the socket spec?

Can this socket accept the 0.025" square-pin header?  It looks like it wants round-pins - typically more expensive. 

Stan, this is from the full spec sheet.

The DCSRC holes appear to be approx. 1mm as closely as I can see it with a MM ruler and my old eyes anyway. Pretty close to the 0.040". The pin headers I have on the bench right now are slightly smaller than 1mm, either square or slightly rectangular, as nearly as I can see. I don't have anything to actually measure the 0.025" with, but I think we may be in the ballpark.  

Datasheet says 0.040" +/- 0.003 so perhaps OK.  Do you have a numbered drill-bit set?  #61 bit is 0.039, #60 bit is 0.040", #59 bit is 0.041".   Looks like GRJ confirmed socket can accept the 0.025" square-pins you most likely have.  Yes, if you're only offering a bag of parts requiring soldering then 93 cents for a press-fit socket may not be a good bang for the buck.

You need a good set of calipers.  Here's what I use, very handy as they have both inch and mm readings.  I got tired of the batteries always being dead in the digital ones, and went for these.

SHARS 6" 150mm Inch Metric Dual Reading Dial Caliper MM

stan2004 posted:

Yes, if you're only offering a bag of parts requiring soldering then 93 cents for a press-fit socket may not be a good bang for the buck.

I was thinking more along the lines of assembled versions.  The 555 board should be easy to assemble pretty quickly, and reach a wider audience.