LED bar graph

[[email protected]]

Alright, I have been trying for the past couple of months to create
this LED bar graph--the premise for the circuit was this: when the
circuit was turned on, it would light up a 2x5 matrix of LED's in
sequence, where after about 4 seconds, all of the LED's would be lit.
I have considered having capacitors in parallel with each line of LED's
so that the LED's acted as a sort of indicator as to how full the
capacitor was....I had some trouble with that. If anyone can steer me
in the right direction, I would appreciate it.

Thanks!
grant

 

[Don Taylor]

Alright, I have been trying for the past couple of months to create
this LED bar graph--the premise for the circuit was this: when the
circuit was turned on, it would light up a 2x5 matrix of LED's in
sequence, where after about 4 seconds, all of the LED's would be lit.
I have considered having capacitors in parallel with each line of LED's
so that the LED's acted as a sort of indicator as to how full the
capacitor was....I had some trouble with that. If anyone can steer me
in the right direction, I would appreciate it.

A couple of ideas,

The LM3914 is a single chip that might work for you. You can google
for it or for LED bar graph and you should find example circuits.
You would want to give this a triangle wave input that ramped up to
maximum voltage in 4 seconds. An op-amp, a capacitor and a couple
of resistors can help you create something like that.

The single chip microcontrollers could be programmed to do something
like this. This is much more of a software approach to solving your
problem. You would create a timing loop and have the program set
the pins low and high to turn your leds on and off.

You can toss me mail if you want me to be more specific.

 

[John Fields]

On 28 Sep 2005 23:02:36 -0700,

Alright, I have been trying for the past couple of months to create
this LED bar graph--the premise for the circuit was this: when the
circuit was turned on, it would light up a 2x5 matrix of LED's in
sequence, where after about 4 seconds, all of the LED's would be lit.
I have considered having capacitors in parallel with each line of LED's
so that the LED's acted as a sort of indicator as to how full the
capacitor was....I had some trouble with that. If anyone can steer me
in the right direction, I would appreciate it.

---
View with a fixed-pitch font like Courier:


7555 +5v +5v
+-------+ +-------+ | |
+--|TH R|----+ | D1|--+ ALL 2N4401 |
| |___ | | | | C-+-[270R]--[<LED]-+
+-O|DIS OUT|--+-|--|> Q1|--+--[1KR]-----B | |
| +-------+ | | | | | +---E +-[270R]--[<LED]-+
| | | | D2|--+ | |
+---[1.2M]----+ | | | | C-+-[270R]--[<LED]-+
| | | Q2|--+--[1KR]--|--B | |
[0.47µF] | | | | +---E +-[270R]--[<LED]-+
| | | D3|--+ | |
GND | | | | C-+-[270R]--[<LED]-+
| | Q3|--+--[1KR]--|--B | |
| | | | +---E +-[270R]--[<LED]-+
| | D4|--+ | |
| | | | C-+-[270R]--[<LED]-+
| | Q4|--+--[1KR]--|--B | |
| | | | +---E +-[270R]--[<LED]-+
| | D5|--+ | |
| | | | C-+-[270R]--[<LED]-+
Vcc | | Q5|--+--[1KR]--|--B | |
| | | | | +---E +-[270R]--[<LED]-+
[100K] +--|Q6 D6|--+ |
| |_ | GND
+-------|R |
| +-------+
[0.1µF] 74HC174
|
GND

 

[John Fields]

Alright, I have been trying for the past couple of months to create
this LED bar graph--the premise for the circuit was this: when the
circuit was turned on, it would light up a 2x5 matrix of LED's in
sequence, where after about 4 seconds, all of the LED's would be lit.
I have considered having capacitors in parallel with each line of LED's
so that the LED's acted as a sort of indicator as to how full the
capacitor was....I had some trouble with that. If anyone can steer me
in the right direction, I would appreciate it.

---
View with a fixed-pitch font like Courier:


7555 +5v +5v
+-------+ +-------+ | |
+--|TH R|----+ | D1|--+ ALL 2N4401 |
| |___ | | | | C-+-[270R]--[<LED]-+
+-O|DIS OUT|--+-|--|> Q1|--+--[1KR]-----B | |
| +-------+ | | | | | +---E +-[270R]--[<LED]-+
| | | | D2|--+ | |
+---[1.2M]----+ | | | | C-+-[270R]--[<LED]-+
| | | Q2|--+--[1KR]--|--B | |
[0.47µF] | | | | +---E +-[270R]--[<LED]-+
| | | D3|--+ | |
GND | | | | C-+-[270R]--[<LED]-+
| | Q3|--+--[1KR]--|--B | |
| | | | +---E +-[270R]--[<LED]-+
| | D4|--+ | |
| | | | C-+-[270R]--[<LED]-+
| | Q4|--+--[1KR]--|--B | |
| | | | +---E +-[270R]--[<LED]-+
| | D5|--+ | |
| | | | C-+-[270R]--[<LED]-+
Vcc | | Q5|--+--[1KR]--|--B | |
| | | | | +---E +-[270R]--[<LED]-+
[100K] +--|Q6 D6|--+ |
| |_ | GND
+-------|R |
| +-------+
[0.1µF] 74HC174
|
GND

---
Oops... The 7555's reset is low true, and for the symmetrical
astable TH should be connected to TR\. Also, any general purpose
small-signal NPN will work. Orr get rid of the base resistors and
use 2N7000s.


+5v
|
[10K]
7555 | +5v +5v
+-------+ | +-------+ | |
+--|TH OUT|--+-|--|> D1|------+ ALL 2N4401 |
| |__ _| | | | | C-+-[270R]--[<LED]-+
+-O|TR R|O-|-+ | Q1|--+--[1KR]-----B | |
| +-------+ | | | | | +---E +-[270R]--[<LED]-+
| | | | D2|--+ | |
+---[1.2M]----+ | | | | C-+-[270R]--[<LED]-+
| | | Q2|--+--[1KR]--|--B | |
[0.47µF] | | | | +---E +-[270R]--[<LED]-+
| | | D3|--+ | |
GND | | | | C-+-[270R]--[<LED]-+
| | Q3|--+--[1KR]--|--B | |
| | | | +---E +-[270R]--[<LED]-+
| | D4|--+ | |
| | | | C-+-[270R]--[<LED]-+
| | Q4|--+--[1KR]--|--B | |
| | | | +---E +-[270R]--[<LED]-+
| | D5|--+ | |
| | | | C-+-[270R]--[<LED]-+
+5v | | Q5|--+--[1KR]--|--B | |
| | | | | +---E +-[270R]--[<LED]-+
[1M] | | D6|--+ |
| | |_ | |
+----------|-O|R Q6|--+ GND
| | +-------+ |
[0.1µF | 74HC174 |
| C |
GND 2N4401 B---[100K]---+
E
|
GND

 

[[email protected]]

At the risk of sounding completely ignorant...I don't follow you.
heh--
the 7555 could just be any 555 timer, I'm assuming...but what is the
74HC174 doing here?

 

[John Fields]

On 29 Sep 2005 12:00:04 -0700,

At the risk of sounding completely ignorant...I don't follow you.
heh--
the 7555 could just be any 555 timer, I'm assuming...but what is the
74HC174 doing here?

---
It's a shift register.

CLK Q1 Q2 Q3 Q4 Q5 Q6
---|----|----|----|----|----|----
0 0 0 0 0 0 0
1 1 0 0 0 0 0
2 1 1 0 0 0 0
3 1 1 1 0 0 0
4 1 1 1 1 0 0
5 1 1 1 1 1 0
6 1 1 1 1 1 1