💾 Archived View for gem.librehacker.com › gemlog › tech › 20211008-0.gmi captured on 2021-12-04 at 18:04:22. Gemini links have been rewritten to link to archived content
⬅️ Previous capture (2021-11-30)
-=-=-=-=-=-=-
Gikfun Infrared Reversing Radar project - completed
I finished soldering this little DIY reversing radar project, my first soldering projecting involving SMT. As you can see if you look closely at the above photo, the soldering results were not beautiful, with a lot of variation and bumpiness in the resistor soldering joints, and a lot of ugliness on the joints for those two tiny TSSOP ICs. But, for all that, the device seems to be working fine. As I move my hand towards the receiving diode, the green LED lights up, and then the yellow, and then the red, as expected.
RP1 variable resistor controls the distance at which the LEDs light up. I'm honestly not sure exactly what RP2 does — I'm going to have to study the schematic some more. The basic concept of the board, as I understand it, is that the NE555 chip (the smaller IC) generates the pulses to be sent out the transmitting infrared LED. The signal that is received back is processed by the four op-amps on the larger LM324 IC. One op-amp amplifies the signal, while the other three are used in conjunction with a voltage divider network to do voltage comparison, and light up each of the color LEDs at the appropriate threshold of received signal amplitude.
I'd like to try hand-soldering with larger SOIC ICs, which have larger leads, to see if that is significantly easier. I'm not sure if I'm too eager to do any more hand-soldering projects involving these tiny TSSOP ICs, though it is doable.
My understanding, from some brief Internet research, is that the cool kids these days are not hand-soldiering their SMT components, but instead using special solder pastes which you squeeze onto the pads, and then you heat the joint up with a non-contact torch. I might have to explore that some more.
Anyway, this gikfun DIY kit was worth the money, with some caveats:
- Kit was complete without any missing pieces.
- Instruction sheet was good with schematics, tips, and a component list. The English was fairly good though obviously E2L.
- Final product works as expected.
- The main downside was that it uses the TSSOP ICs with very small leads. If you are learning SMT soldering for the first time, maybe a project with larger IC leads would be a nicer introduction.
- The power leads provided do not include any connector on the other end. So if you don't happen to have a clip-on 9 volt power supply, you'll need to attach something like a 9 volt battery connector, or use alligator clip jumpers.
