PCB assembly discussion

[Tony]

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.

[Riddler357]

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

[Riddler357]

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

[Tony]

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.

[Riddler357]

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

[vtluu]

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...

[Tony]

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.

[Higginz]

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!

[Tony]

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.

[Bernieb627]

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?