I am a complete beginner in electronics and started 3 weeks ago to build a display sign with leds forming letters on a foam board. (each in parallel with each a 330 ohm resistor on the positive lead)
On a breadboard i succeeded in making a circuit with a 555 chip and a 4017 chip because I would like the first word (four-lettered, about 80 leds) to flash as a whole and the second word (8 letters of about 20 leds each) to flash sequentially. I power it with a wall-mart. I placed one led to represent the first word, out of the 555, and 8 leds to represents the letters of the second word, and it flashes nicely.
Now I am stuck because I need to amplify the power out of the ics, I think. I tried to place a 2n2222 transistor out of one of the pins of the 4017, with a 1.5 k resistor before and replaced the led with a flash light bulb rated 500 mAmps (I don´t want to test it directly on my sign and risk losing hours of soldering work) but it does not light up.
the I left the transistor in place and put back the led instead of the bulb and it flashes.
I imagine I need 500 mAmps for each letter, and about 1.6 Amp for the first word, but I cannot figure what transistor to use.
Maybe I can connect the load directly to the power source and then power the circuit with a battery ? Is that possible ?
I would be very thankful for some help
On a breadboard i succeeded in making a circuit with a 555 chip and a 4017 chip because I would like the first word (four-lettered, about 80 leds) to flash as a whole and the second word (8 letters of about 20 leds each) to flash sequentially. I power it with a wall-mart. I placed one led to represent the first word, out of the 555, and 8 leds to represents the letters of the second word, and it flashes nicely.
Now I am stuck because I need to amplify the power out of the ics, I think. I tried to place a 2n2222 transistor out of one of the pins of the 4017, with a 1.5 k resistor before and replaced the led with a flash light bulb rated 500 mAmps (I don´t want to test it directly on my sign and risk losing hours of soldering work) but it does not light up.
the I left the transistor in place and put back the led instead of the bulb and it flashes.
I imagine I need 500 mAmps for each letter, and about 1.6 Amp for the first word, but I cannot figure what transistor to use.
Maybe I can connect the load directly to the power source and then power the circuit with a battery ? Is that possible ?
I would be very thankful for some help