My "Shinny" Seq V2

[atomsize]

;D

Almost finished...

Right now it's all connected, AIN's DOUT's Core and LCD's (The lcd's are thoses that need the inverter for working, done that too).

Now my problem is the next; i've build a simple pwer supply for testing the seq. a 15v AC trafo, with some electro caps and a 5v regulator. i also putted a led in the end to be shure that the power supply was working.

My sequencer have blue and white leds (3mm)

i turn on the power supply (without connecting it to the seq.) and i see the power led on... i connect the core (that is already connected to the modules and lcd's) and the power led fades, no leds are on, no lcd data, and only a voltage of 2.3 volts in the core J2.

The trafo is a 15v 1 Amp power. What could be making this voltage drop? The led's (they were sold as 7000mcd's brightness), the LCD backlight?

thank you all for helping :)

[moxi]

hi,

the blue led need more curent than other,maybe you have to change the resistor on DOUT  according to this fact.

For a red LED the "characteristic voltage" is 1.7v.

For an orange LED the "characteristic voltage" is 1.9v.

For a green LED the "characteristic voltage" is 2.1v.

and the blue ones often more!

this quote is taken from this page:

http://www4.tpg.com.au/users/talking/25mA.html

but i can't affirm that it's the source of the problem you have  ,if the current @ your core is only 5V ,maybe is too less ,my seq have the same problem if i put my wall transfo on only 6,5V ..

[atomsize]

i have a 470 ohm resistor in all leds, blue and white

should i replace for a lower one (i dont want too much bright on them) or i can go with a 8v power supply?

thanks :)

[seppoman]

i turn on the power supply (without connecting it to the seq.) and i see the power led on... i connect the core (that is already connected to the modules and lcd's) and the power led fades, no leds are on, no lcd data, and only a voltage of 2.3 volts in the core J2.

The trafo is a 15v 1 Amp power. What could be making this voltage drop? The led's (they were sold as 7000mcd's brightness), the LCD backlight?

I think the problem is the 15V supply. When a 7805 is driven with 15 Volts, it converts 2/3 (two thirds!!!) of the energy into heat. Even If you had a huge heat sink attached (which I don´t see on the picture), the 7805 would probably become too hot. When a regulator gets too hot, the voltage drops. If you don´t need more than 5 V anywhere in the box, better use a 7.5V supply. Even then, the two LCD backlights probably use quite some power. If you drive them both from the core, the 7805 has to be cooled (large heat sink or put wires between the board and the regulator and mount it somewhere on the metal case). If this is not enough, you could build a small extra rectifier/regulator portion for the second LCD.

Seppoman

[seppoman]

the blue led need more curent than other,maybe you have to change the resistor on DOUT  according to this fact.

As the LED voltage of blue ones is higher, the current with the standard 220 Ohm resistors is even lower than with other colours.

I = U / R, where U = 5V - LED voltage. So when Led voltage is higher, the current goes down.

So with standard resistors, the blue LEDs simply are not as bright as they could be. Use lower resistor values to make them brighter but take care the current doesn´t get higher than 20mA per LED.

but i can't affirm that it's the source of the problem you have  ,if the current @ your core is only 5V ,maybe is too less ,my seq have the same problem if i put my wall transfo on only 6,5V ..

You´re mixing up something here. current is measured in Ampere, not Volt. Voltage on the core (after the regulator - and therefore also at the LEDs) should always be 5 V or you would fry the PIC.

When you have your wall wart at only 6.5 V, the voltage drops because the 7805 needs at least 7 V to produce a stable 5 V voltage. So 7.5 V supply is the best value for any box that doesn´t use anything besides 5 V.

Seppoman

[moxi]

hi ,

you're right about my mistake ,i've used the word "current" in this general meaning.

but atomsize wrote :

i've build a simple pwer supply for testing the seq. a 15v AC trafo, with some electro caps and a 5v regulator.

so i was thinking he build a power supply that already down the VOLTAGE ;)  to 5V before the regulator already present on the CORE  .

atomsize :it's what you do? if yes ,the reply of seppoman give you the right answer when he said :

When you have your wall wart at only 6.5 V, the voltage drops because the 7805 needs at least 7 V to produce a stable 5 V voltage. So 7.5 V supply is the best value for any box that doesn´t use anything besides 5 V.

(great thank for this info)

if not ,his first answer is the good one .

Voltage on the core (after the regulator - and therefore also at the LEDs) should always be 5 V or you would fry the PIC.

i'm talkin about voltage before the regulator ,of course...

now ,i will go back do some exercises about the Ohm law!!! ;)

[d2k]

Hey,

I've used those ultrabright blue leds in boxes before (lc, sid) and used 470r resistors instead of the 220's but still found em too bright...latest box (mbfm) i used em again but raised the dout res's to 5K6 (they was to hand) which works great - i can look at the panel and not be blinded now!

[MMorph]

Right now it's all connected, AIN's DOUT's Core and LCD's

What's the function of the AIN module or just a typo of DIN?  ???  For your problem then, you could try to disconnect the backlight of LCD's to reduce the need of current and see if that temporary solves the problem. Just like seppoman, I'd as well recommend feeding the 5V regulator with less that 15V. Otherwise it produces alot of heat. And there are no shorts of any of kind, right?

Regards, Petri