im a beginner at electronics. im trying make an drawdio circuit with the instructions in the link below: http://www.ladyada.net/make/drawdio/drawdio2schem.png i have following components on the circuit.

  • NE555N 555 timer
  • PN2907 transistor
  • 100uF 25V capacitor (instead of 6.3v one on the ladyada's page)
  • 680pF ceramic capacitor
  • 0.1uF non-ceramic capacitor ( instead of ceramic one on ladyada's page)
  • 1/4W 5% 10 MEGAohm resistor
  • 1/4W 5% 10 ohm resistor
  • 1/4W 5% 300K resistor
  • Small 8ohm speaker 0.5w

do you think any of those changes i made might be causing low sound problem?? please help :/

  • \$\begingroup\$ All the components and values sound like they're ok. Just a brief point, did you connect all 5 Vcc connections to the positive of the battery? It's also worth checking to see if you put the electrolytic capacitor the right way round \$\endgroup\$
    – Jim
    Oct 5, 2010 at 11:58
  • \$\begingroup\$ i connected wires as it is shown in the circuit scheme. \$\endgroup\$ Oct 5, 2010 at 12:18
  • 3
    \$\begingroup\$ Try asking at forums.adafruit.com \$\endgroup\$ Oct 5, 2010 at 12:32
  • \$\begingroup\$ That design doesn't seem too robust on the audio amp section. You might want to try hooking this up to a general purpose amplified speaker. \$\endgroup\$
    – J. Polfer
    Oct 5, 2010 at 12:51
  • \$\begingroup\$ After looking at the Drawdio website, they all seem to be quite loud even the one's using the circuit design you've linked to, you might need to post a picture of your circuit so we can check it visually for anything that's obvious. I also agree with Joby too, the Adafruit forum would be a good port of call. \$\endgroup\$
    – Jim
    Oct 5, 2010 at 13:16

1 Answer 1


Does ladyada recommend the 2N2907? I did not see a label on the schematic.

Since the transistor is being used as a switch a better choice would be a 2N3906 which has much lower Vbe(sat) and Vce(sat) specifications.


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