Suggestions for improvements, mistakes, hints here please.

Hello,
I completed assembly my nixie thermometer here a picture of it!
It work great except for one thing, when I power up the nixie thermometer it show the right temperature, but after a couple of hours running, the thermometer show a temperature around 5 degree higher than the reality.
This is obviously caused by the heat of the circuit. This could be corrected by adding a software compensation.
I was wondering if it possible to get the microcontroller source code, so I could try adding an offset in the temperature reading to have a more accurate thermometer.

Hey guys,
I received my kit today and started assembling it, but then got to the LED step and ran into a problem. 1 of the 5 LEDs has the flat side on the opposite side from the rest. Suggestions?
I went ahead and mirrored the anode/cathode layout of the other 4 for this one, but please let me know if one was actually supposed to be 'off'.

You did remeber the silicone pad under the temp sensor IC? - that thermally couples it to the case itself. There will always be some self-heating with an internal sensor, there's an option for an external sensor I'll be adding the instructions for shortly.
I have no objection to releasing the source as long as you don't mind the kludges and lack of comments in places, but I'll ask thinkgeek first to make sure it's OK with them.

lostpckt wrote:
Hey guys,
I received my kit today and started assembling it, but then got to the LED step and ran into a problem. 1 of the 5 LEDs has the flat side on the opposite side from the rest. Suggestions?
I went ahead and mirrored the anode/cathode layout of the other 4 for this one, but please let me know if one was actually supposed to be 'off'.
Thanks for pointing that out, I've checked the LEDs here and the notch doesn't appear to be used to indicate polarity on these as I expected it should. To clarify it, the notch should be next to the short pin - I've amended the instructions.
One of the two rightmost LEDs will be off, which will depend on the symbols needed at that part of the cycle.

Another question (can you tell how far I'm getting?).
In the picture
http://www.lasermad.com/instructions/therm/31.JPG
(not sure what step it is, step numbers?) it shows R28 still open, and the following steps use it for debug/diag before final assembly.
In pictures
http://www.lasermad.com/instructions/therm/34.JPG
and the following one (38.JPG, but not allowed to link to it), there is clearly something soldered into R38. Is there a step missing where the .47R fusible resistor should be soldered in? Or am I blind and missing it?
Thanks!

Ignore the resistor in that photo, it was just the best available to show the nixie anodes. The .47R is the very last component you want to put on the board, once everything else has been tested and is working.

Hey Tony, me again
Sorry for all these posts. I've managed to get up to first "power it on stage" but am not seeing any light from any LED (which one is supposed to light up?). Unfortunately, my MM doesn't do mA (just amps), but I get a flat 0.0 across R28 when plugged in. I've run across the board testing everything I can think of, and everything seems to be correct. Would you mind if I emailed you some macro shots of my work so far and maybe you can spot something I've missed? Or perhaps give some additional troubleshooting hints on what may be wrong?
Thanks, and this project is great. It's clearly "the next step" for me as kits I've worked on previously have been zero troubles (it's a GOOD thing to be pushed!!)

Hi,
Not a problem, please send them and I'll have a look. Silly question first though, the power supply is working and providing 5V?.

Yup, 5.5V from pin to ground. That was the first thing I checked

I'm going ahead with my construction, but can i safely assume (after a set of random tests) that the holes in the PCB are plated through?? Do I need to solder resistors on both sides?
Thanks!
jack

They're through hole plated so you only need to solder one side.

Hello World!
Hello everyone
My name is Victor and had a couple of questions about this project. First just to let you know that i have been building electronic devices for years and everyone of them worked the first time, example 8x8x8 led cubes(not powered by arduino boards) larson scanners, and different robots. This project seemed to be pretty easy project to be put together. I got up to the first test part and found that the LED's were not working except for the ir one. So did some trouble shooting and didn't find anything out of the norm. The leds work because i always check LEDs before i put them into a project. So i was wondering if you had a wire diagram of your work. I could just use the PCB but would like something i can follow. I would really love to get this working.
Thanks Victor

If the IR led is working the controller is probably OK. There was a problem using the notches to identify polarity and the instructions were amended to mention it though you've probably built it since then.
There's really not a lot that can go wrong here if the PIC is working, could you measure current being drawn and the voltage across the LEDs and let me know.

lostpckt wrote:
I received my kit today and started assembling it, but then got to the LED step and ran into a problem. 1 of the 5 LEDs has the flat side on the opposite side from the rest. Suggestions?
I went ahead and mirrored the anode/cathode layout of the other 4 for this one, but please let me know if one was actually supposed to be 'off'.
I had the
exact
same issue, and dealt with it the same way you did (which appears to be the correct answer).

lostpckt wrote:
I've managed to get up to first "power it on stage" but am not seeing any light from any LED (which one is supposed to light up?). Unfortunately, my MM doesn't do mA (just amps), but I get a flat 0.0 across R28 when plugged in. I've run across the board testing everything I can think of, and everything seems to be correct. Would you mind if I emailed you some macro shots of my work so far and maybe you can spot something I've missed? Or perhaps give some additional troubleshooting hints on what may be wrong?
I'm currently at this stage and in the same predicament, though I've done less debugging so far (will next have time to spend on it this weekend).
I'm worried I may have really borked things, because in the process of soldering on the surface-mount IC, one of the pads came off the PCB. I *think* it was intentionally shorted to the other pads in which case I could just substitute a solder bridge, but I'm not sure.
Worse comes to worse I hope I can purchase a replacement PCB + first-step components (not including the expensive stuff, namely the tubes) and start over.
In hindsight I
should
have taken detailed photos of back of the blank PCB so I would know for sure what's an inadvertent solder-bridge (two close solder points shorted together that aren't supposed to be touching) and solder points that are close and connected by design.
Tony
, is there any chance you could provide such a photo? Thanks!

Have a look in the 'troubleshooting' thread for the PCB layout. Could you check the voltage across the LEDs and at pin 14 of the PIC. There's very little to go wrong in hardware that can prevent the LEDs working. The PIC can hang before that stage though if it doesn't receive a signal from the sensor - without any data there's nothing to display so they're switched off.
Check first:
MPSA42 and 92 transistors haven't been mixed up
Voltage across LEDs
Supply to PIC (though if the IR LED is working it should be on)
Bridges around the SMD IC, the DHT11 and the 5k6 resistors.
Let me know the results.

Just realised that I replied to the wrong question
Just to clarify, is your problem no current at all being drawn?. (we fixed that one via emails)
vtluu wrote:
lostpckt wrote:
I've managed to get up to first "power it on stage" but am not seeing any light from any LED (which one is supposed to light up?). Unfortunately, my MM doesn't do mA (just amps), but I get a flat 0.0 across R28 when plugged in. I've run across the board testing everything I can think of, and everything seems to be correct. Would you mind if I emailed you some macro shots of my work so far and maybe you can spot something I've missed? Or perhaps give some additional troubleshooting hints on what may be wrong?
I'm currently at this stage and in the same predicament, though I've done less debugging so far (will next have time to spend on it this weekend).
I'm worried I may have really borked things, because in the process of soldering on the surface-mount IC, one of the pads came off the PCB. I *think* it was intentionally shorted to the other pads in which case I could just substitute a solder bridge, but I'm not sure.
Worse comes to worse I hope I can purchase a replacement PCB + first-step components (not including the expensive stuff, namely the tubes) and start over.
In hindsight I
should
have taken detailed photos of back of the blank PCB so I would know for sure what's an inadvertent solder-bridge (two close solder points shorted together that aren't supposed to be touching) and solder points that are close and connected by design.
Tony
, is there any chance you could provide such a photo? Thanks!

Thanks for the quick reply Tony. I didn't have my multimeter with me at the time so I couldn't measure current or anything, only visually inspect everything. Unfortunately I won't have time to pick up this project again until Saturday... But when I do, I'll check everything you mentioned and report my findings here.

Hello World!
Hello again,
So here is what i did, I really didn't care for the LED's being there in the first place, so i went ahead and did the rest of the project without the LED's. Got everything in and and did the second part of test, so when i plugged it in, again nothing lit up:( at this point i figured that the LED's are part of the circuit. So i started to test with the circuit using the amp scale. When i touched one end of my meter to where the power side of the LED was ..the nixie tube lit up and started to go through its numbers. So I put the LED's back in and when i plugged it in nothing came on. I tried different LED's same size and again nothing happened. I put some 100k resisters in and it started to light up again. I really don't care for the LED's being there, but if i have to have them there why does it only work when i put a dummy load on it?
Thanks
Victor

The LEDs are part of the circuit and are in series with the tube anode switching transistor bases. If you don't want them (I don't like the idea of sticking plastic LEDs under nixies but it seems to be the current fashion) replace them with a low value resistor, say 1k. 100K may be a little high to bias the MPSA42.

Hello World!
Hello Again
So i replaced the 100 k with a 1 k and works great thanks
All the functions work too. Great little project I love it Thanks. IF you you know of more like projects please let me know i love doing this kind of stuff
Victor

Hello World!
Hello again
I am having a little problem with the project, it seems to go through all the modes without waving anything in front of it. I was wondering if i could replace the IR with a button or a different switch to activate the modes??
Thanks
Victor

Not woithout modifying the code. Have you tried changing the led and sensor angles to reduce sensitivity and is it in the case or still a bare PCB?. If that doesn't work unsolder one of the IR LED legs to eliminate external IR interference as a problem.

Hello World!
Hello Again
so i have figured out why the modes kept on changing, the reflection of the nixie on the ir kept changing the mode so i dulled the area around the ir led and the mode doesn't change all the time. When i wave my have over it real close it changes. I think i am good now Thanks for the Advice Tony
Victor

Tony wrote:
Have a look in the 'troubleshooting' thread for the PCB layout. Could you check the voltage across the LEDs and at pin 14 of the PIC. There's very little to go wrong in hardware that can prevent the LEDs working. The PIC can hang before that stage though if it doesn't receive a signal from the sensor - without any data there's nothing to display so they're switched off.
Check first:
MPSA42 and 92 transistors haven't been mixed up
Voltage across LEDs
Supply to PIC (though if the IR LED is working it should be on)
Bridges around the SMD IC, the DHT11 and the 5k6 resistors.
Let me know the results.
Double-checked the transistors, they're in the right place. With the R28 resistor sitting (but not soldered) in place voltage across the LEDs is around 0.7 V. Voltage at the USB power supply and across the power rail is 5.2V. Same at the PIC.
Connecting my multimeter across the R28 holes (without a resistor in place) I'm measuring a current of 28 mA.
Will check that last item tonight. My SMD is a bit beat up from me soldering it, thinking I got it wrong and desoldering it, then re-soldering it...

The current reading is about right, maybe a litthe high if the LEDs are off. Can you see a faint red glow from the IR LED? and do any of the blue LEDs light at any point?. If the IR LED is working there's a chance it's started in 'off' mode, try waving your hand over the IR LED and sensor to try changing it.

Hey Tony!
I bought one of these last weekend and finished it in about 4 hours Thursday night. Looks great and worked fine on first power up! Just a few questions:
I am having the common 'Temperature reading too high' as mentioned on another thread, especially after first turning the thermometer on. The temperature climbs about 8 degrees F higher than ambient and stays there. I did place the sticky pad in the correct location, but im guessing it is reading latent heat from the inside of the case. Is there any fix other than using an external probe?
All the tubes and LEDs light and work properly, but the blue LEDs seem dim. See picture. They are not really noticeable with the case assembled. Any way to increase the brightness?
Thanks!

You can try changing the coil L1 for a 33uH, this will reduce the HV output slightly and lower the heat generated.
To increase the LED brightness reduce the value of the 1k2 resistors to 680-820R though they're intended to be dim.

I have a few IN 19A tubes that don't have all the leads. For the thermometer, do I only need the anode, %, C, and K? If the anode is pin 1, what pins are they counting clockwise when looking at the bottom of the tube?

Yes, or less depending on the temperature ranges you want to display. The short pin at the front is counted as pin 1, from there it's %2, C14, K10 and the anode is pin 8.

Which ir led goes with the metal sensor? I need to know the wavelength value...

it's the one WITHOUT brown tape, 940nm.