Picaxe hiccup

[Protezoid]

Hi group

This is my first post. I have been programming Picaxe for 2 months now and experimenting with RGB bleeder effect to learn commands. When i close my desktop neon lamp to better see the rgb LED, the picaxe jumps in the sequence of colors like it was disrupted. Both are connected to the same surge protected ac supply extension cord. The 14m2 is powered on a standard 7805 circuit, a capacitor recommended for all ICs is also between V+ and 0v. Besides this glitch, everything works well. Is the picaxe sensible to high voltage transformers like ones used to power neons or is there a way to prevent this for future project where disrupting devices should be connected on the same ac power outlet?

Thanks,
Protezoid

 

[premelec]

Welcome to this forum... it's hard to know from your description just what the situation is - perhaps you could post a picture - when you refer to to neon lamp it could be a 15,000 volt unit or 50 volt and a transformer or flyback etc... One thing for sure is that you should tie down all unused PICAXE inputs and bypass the PICAXE power pins close to the socket with at least .1 uF ceramic cap. Have you tried electrostatic shielding? Strong electric fields can certainly affect electronics such as a PICAXE...

 

[Goeytex]

Is the picaxe sensible to high voltage transformers like ones used to power neons or is there a way to prevent this for future project where disrupting devices should be connected on the same ac power outlet?

All CMOS devices are sensitive to high level noise spikes, especially microcontrollers that are designed to reset with a low voltage power spike.

Having the Picaxe power source and and neon lamp (transformer) on the same "extension cord" is a generally bad idea, especially if the lamp is a cheapo made in you know where with no noise suppression.

1. Connect any unused Picaxe Pins to ground through a 10K or 4K7 resistor.
2. Move the lamp as far away from the Picaxe as possible and see what happens.
3. Try a different power supply for the Picaxe ( Are you using a "wall wart" right next to the neon transformer ?)
4. Temporarily add the command "DISABLEBOD" at the beginning of the Picaxe code to see if the problem stops.
5. Ditch the neon lamp and use an incandescent or LED type
6. Shield the Picaxe circuitry in a grounded metal enclosure.

Good luck.

 

[manuka]

Protezoid: Welcome! Where in Canada are you? Neon light (orange!)? Do you mean fluorescent?

Aside from Goeytex's fine advice you can of course just run the PICAXE setup off a few alkaline AA cells. Batteries greatly simplify overall PICAXE circuitry as well, especially if housed in a switched AA battery box (see below). Three cells(~4.5V) give more supply headroom, but just 2 (~3V) can do in many simple setups. Such layouts have been the standard here in NZ for a good 10 years - 1000s have probably been mde on my watch alone!

As Forum regulars know only too well,I've however become a big fan of rechargeable 3.2V LiFePO4 cells. Only a single such AA sized 14500 LFP type works well in many PICAXE applications. All circuitry,including the battery, can often be fitted inside a partially gutted 3 or 4 x AA battery box!

Extra: Perhaps also check fellow Kiwi Andrew Hornblow's long standing "smell of an oily electron" approaches => https://picasaweb.google.com/picaxe

 

[Protezoid]

Thank you all for your good advices

I'm using the Picaxe on a breadboard and the fluorescent (not neon!) lamp is a small 20 w desktop Ott-Lite which is right over the breadboard. My computer, lamp and Picaxe are all connected to a battery pc backup UPS with surge protection. I also have a 27'' monitor near my breadboard and recently i saw the same problem when i turned it off, the Picaxe seems to reset, so it must be spikes! I thought that a surge protector would prevent from spikes? I will try your recommendations and give you feedback. This problem was easy to see because i was using an RGB led color sequence and visually saw that something was wrong. This should be a good experiment to prevent 'malfunctions' from nearby devices in the future when testing with unshielded breadboards. To know if a Picaxe has reseted since it was turned on, i guess the use of Time counter would be be a way?

I live in the province of Québec, Canada, near Montreal. The only store that sells Picaxe here is not so good. I was given a limited 08M2LE instead of 08M2+ and had lots of troubles for my first experience with Picaxe because of bad advices from the start. Gonna use the good people of the forum instead

Thanks

 

[BeanieBots]

Fluoroescent lamps are notorious for both surges and radiated noise.
A surge protector will help but it won't cure all the problems with high current and/or voltage switching noise.
To detect if you have had a reset, simply put a sertxd or flash an LED near the start of your code.

To help eliminate the problem, make sure you have good decoupling, no long leads near mains leads, all inputs tied down.
Think about how you would reduce hum in an audio amplifier and apply the same principles.

 

[erco]

Welcome, Protezoid! Montreal is a great city. Unplug the flu lamp from the UPS and plug it into the mains.

 

[tony_g]

I live in the province of Québec, Canada, near Montreal. The only store that sells Picaxe here is not so good. I was given a limited 08M2LE instead of 08M2+ and had lots of troubles for my first experience with Picaxe because of bad advices from the start. Gonna use the good people of the forum instead

Thanks

im guessing you would either be using abra electronics or robotshop? i use solarbotics out west here in calgary,alberta they have never given me any issues, their advice before i started to dive into picaxe was pretty straightforward and helpfull and their prices do seem quite a bit better for a majority of the picaxe range than other suppliers out here


tony