Is there a cheap and small electronic component that generates enough heat to draw on thermal paper? I don't need to draw fast or precisely, I just need it to be able to produce enough heat to "activate" the thermal paper. The best would be something that could work on 12VDC at most. I'm sure there is such a thing, but I just don't know what it is. Any help is greatly appreciated, HEMOglobina
HEMOglobina wrote in news:c2fa36d7-5e5f-47cc-b793- firstname.lastname@example.org:
Use current in a tiny resistor and wipe it across the paper. Or a sharp hairpin bend in a bit of resistance wire... But lasers are fun if you haven't tried them much. Dangerous too though, so if you try, do plenty of reading on forums, and the LaserFAQ, so you know what you're getting into. They're the most effective way to draw on thermal paper if you end up wanting precision.
If you want to try, get a laser diode, such as those in a DVD writer. They're about 100 mW CW (continuous wave), and bright red. You'll need a small aspheric lens, but the lens in the writer mechanism might be enough. It's fiddly work, and you'll need very rigorous anti-static precations. To drive the diode, look at the datasheet for the LM317, wired as a current regulator. You can make that currrent variable to zero by putting a 5K potentiometer across a 1.25V bandgap voltage reference, with one end of this network on the output, AFTER the current limit resistor, on the high side of the load, the other end to ground. Connect the wiper of the pot to the ADJ pin. Also connect a 1K resistor from the pot wiper to ground, so that if the pot wiper goes open-circuit, there is no danger of a surge of high current destroying the laser diode. Laser diodes usually don't tolerate reflections of their own light back into them. They usually die.
Kevin McMurtrie wrote in news:4cff0daa$0$22132$ email@example.com:
That could be useful. it has a fairly high friction, and it's consistent. I wonder if it can be had in tape form, to replace ticker tape. Not as accurate, but nice to have silence and no moving parts except the tape and whatever pulls it.
(I haven't used ticker tape for over 25 years, I just like the idea...)