9. Output devices
When I about 13 years old I started to get interested in electronics, one of the first porjects I made was a speaker with an Lm358, i want to recreate it more professionally, this will also be features on my final project. Its important to fabricate output circuits such as this one because if we don't our microcontrollers could get burn trying to use multiple motors, speakers and other output devices, because they requiere a lot of current. Check Week 9 Guide Ibero Puebla Fablab for support material.
I started by looking for an old drawing of the circuit I made, the one you see above, since it worked I just had to do it in an EDA software, I used EasyEDA. When making output devices our best friends are transistors and op amps, they maintaing current estable and give our circuit gain. For design especifications check my week 8 where I go in depth on how to design a PCB. Because this design does not require a very complicated connection I didn't make a schematic and went directly to the PCB design.
After it was done I fabricated it, to see how to do this check out my week 4 page where I go in depth on how to manufacture PCBs. You can click here to download the traces and here to download the outline.
Finally I took it out of the machine and took it of from the sacrifice plate
Then I soldered the components, for this circuit you will need:
| 100k resistor | 1k resistor | 2.2 uF and 470 uF capacitors | LM358 op-amp | BD139 transistor | 2W speaker | Male pinheaders |
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To connect a battery and a device this is a little schematic of how it shoul be done.
I tested it with my phone and it worked nicely, the battery was low so it didn't reach it's potential.