Author Topic: my booster is a radio  (Read 4881 times)

dubold

my booster is a radio
« on: November 19, 2003, 08:35:34 PM »
aron;

thanks so much for making this project relatively straighforward. I built the NPN boost, wired everything up as per the diagram, with one exception-- replacing one electrolytic capacitor with a film. i grabbed the wrong one at radio shack--

so i finished up the soldering tonight and decided to test the circuit-- i was prepared for the worst, expecting to hear nothing at all from my amp. Instead, i heard a really quiet, non-boosted or distorted signal. it sounds pretty much just like my guitar does clean, only really quiet. I had to literally turn the volume up all the way on the amp to hear it.

and, to make things even odder, when I remove the ground (i was using an alligator clip from my guitar cable to the common ground) the boost becomes a radio, picking up several stations at once.

I am totally new to this, but anxious to learn. any advice/tips/idea what went wrong?

thanks very much

-d

aron

my booster is a radio
« Reply #1 on: November 19, 2003, 09:53:05 PM »
Can you measure the voltages on the transistor pins with respect to ground.

Put the black probe on ground and then touch the pins of the transistor with the red probe. Set your meter on DC volts.

Let me know.

Thanks,

Aron

dubold

voltages
« Reply #2 on: November 27, 2003, 10:04:04 AM »
okay:

directly off the 9v battery, i get 8.94 VDC

(the transistor is NPN silicon, 2N3904 -- i believe you said that can be a subsitute for the one in the plans)

collector: 8.91
base: 8.91
emitter:2.878

does that explain everything? anything? something?

thanks

-d

aron

my booster is a radio
« Reply #3 on: November 27, 2003, 02:23:50 PM »
You have a solder short or wiring short from the collector to base.

The base should not be the same voltage as the collector.

Check your wiring/soldering there.

dubold

checking for shorts
« Reply #4 on: December 03, 2003, 09:39:13 AM »
i set my meter to continuity and poked around; everything seemed okay-- is it possible that overheating the transistor might have caused this? i put it directly on the board-- tried to be careful about how much heat it got, but I'm not sure how much is too much.

thanks

aron

my booster is a radio
« Reply #5 on: December 03, 2003, 02:18:36 PM »
Please recheck the base and collector, they shouldn't be at the same voltage.

Tell me how you oriented the transistor? What do you think the pinout is?