Quick question on 16F628A

[bigal_scorpio]

Hi Eric,

You solved it again!

On the other hand - BU£$£R! that means I have built another pup, or can it be salvaged? I wonder if there is another IC I can use instead or as well as the 54050s? BTW mine are HEF4050BP - is there a 4050 with better specs?

Thanks for the detective work mate, Al

 

[ericgibbs]

Hi Eric,

You solved it again!

On the other hand - BU£$£R! that means I have built another pup, or can it be salvaged? I wonder if there is another IC I can use instead or as well as the 54050s? BTW mine are HEF4050BP - is there a 4050 with better specs?

Thanks for the detective work mate, Al

Hi Al,
I have emailed jose pito telling him is Jumbo clock will not work, let you know if I get a reply.

The only quick fix I could suggest you try , is to remove an LED from each segment, so its approx an 8V LED string and run the 4050's at +9V not 12V.

I dont know how much board space you have.??
But you could use 3 * 74LS07 o/c with a SIL resistors between the 5V PIC signals and the 4050.
Connect the SIL to +12V and use the 74LS07, 12V outputs to drive the 4050 inputs at 12V.

 

[bigal_scorpio]

Hi Eric,

Just had an idea, could I just replace the sinking 4050 lines with a ULN2803 octal darlington and then use discrete pnps for the source lines?

Al

 

[ericgibbs]

Hi Eric,

Just had an idea, could I just replace the sinking 4050 lines with a ULN2803 octal darlington and then use discrete pnps for the source lines?

Al

hi,
UL2803 would invert the signals!

I am just looking at the signals that the PIC outputs, they seem wrong, let me finish my check, get back to you.

 

[mvs sarma]

suppose we use 2803 and instead of common anode we use common cathode? I mean the LEDs of jumbo clock wired reverse. That would compensate for the reversal caused by the ULN2803, perhaps.

 

[ericgibbs]

hi Al,
Look at this image of the sim PIC display.
It shows the Digit select lines are LOW to enable and the segment lines are High to drive the LED, which indicates a Common Cathode LED, not Common Anode.

Note to make it run I had to invert the Sim Digit select lines.

Lets know what you think.

 

[mvs sarma]

jose pino site has a note that reads configurable CC or CA
Pin 3 defines the display type. If you will use common cathode display, connect to negative. For common anode, connect to positive. Here is a example circuit:

 

[ericgibbs]

jose pino site has a note that reads configurable CC or CA
Pin 3 defines the display type. If you will use common cathode display, connect to negative. For common anode, connect to positive. Here is a example circuit:

OK, I will give that a go.

EDIT:
Tried pin 3 all OK, missed that note in the small print, well spotted Sarma.

Works OK as both CA and CC leds

 

[mvs sarma]

it is OK. but how about the final functionality?

Another note i found was The minutes displays are upside down.
https://www.electro-tech-online.com/members/bigal_scorpio.htmlBigal_scorpio, i think i got the reason for the funny display of Minutes !!!

 

[bigal_scorpio]

Hi Eric and Sarma,

So guys whats the final outcome? Can I use 2803 and change PIC pin 3 and 4x 3906's on the high side?

I seem to be very poor at seeing the logic that you guys take for granted. I am definately getting dimmer! At the moment I am seeing a Professor Venneri at the Hallamshire hospital about memory problems. She has ruled out Altsheimers, but admits there is something wrong, even the MRI I had showed nothing significantly wrong so they are carrying on with more tests. Why can't my memory problems be that I forget the useless stuff instead of the stuff I need ! Doh!

Al

 

[mvs sarma]

please wait. don't just increase hardware chunk

How about checking for hemoglobine deficiency in blood. May be little tonics would help you better.

 

[ericgibbs]

hi Al
Look at this option.

 

[bigal_scorpio]

Hi Eric,

Would this new design be software compatible? Also I don't have any of those ICs.

The only buffers I have are all inverters -: HCF40106BE, ULN2803A, ULN2804A, 74HCT04, 74LS05, HCF40106BE. The exceptions being MM74HC244N, and MM74HC367 (one only!) And I only just ordered from Farnell so I would have to wait till I can justify the order (with the missus)!

Would any of those do?

 

[bigal_scorpio]

please wait. don't just increase hardware chunk

How about checking for hemoglobine deficiency in blood. May be little tonics would help you better.

Hi Sarma,

I've had loads of tests, one of the last was a B12 level and most of the checks they did seemed within normal levels. Thanks for the thought though mate.

Al

 

[ericgibbs]

Hi Eric,

Would this new design be software compatible? Also I don't have any of those ICs.

The only buffers I have are all inverters -: HCF40106BE, ULN2803A, ULN2804A, 74HCT04, 74LS05, HCF40106BE. The exceptions being MM74HC244N, and MM74HC367 (one only!) And I only just ordered from Farnell so I would have to wait till I can justify the order (with the missus)!

Would any of those do?

hi,
That 74LS07 circuit will be compatible with Common Anode, the series resistors will limit the LED current.

I will look see what we can do with the ULN's, the rest of your list is not usable. Dont reorder yet, I think I have some LS07's to spare.

PM me your address,

E

BTW: the LS07 can sink upto 40mA, so keep the LED DIGIT current less than say 25 to 30mA

 

[ericgibbs]

hi Al,
It can be done using ULN2803 and the 74LS07 but its an awful circuit.!!!! power waster!

If you want to use the same hex program I could draw you a new circuit using transistors.?

 

[bigal_scorpio]

Hi Eric,

Thanks mate, that would be awesome. I have built my digits and driver on separate boards so building another driver circuit would be much more palatable than changing the LED digits around, though I could if necessary.

Thanks Eric, I will await your circuit.

Al

 

[ericgibbs]

Hi Eric,

Thanks mate, that would be awesome. I have built my digits and driver on separate boards so building another driver circuit would be much more palatable than changing the LED digits around, though I could if necessary.

Thanks Eric, I will await your circuit.

Al

Hi Al,
Which type of PNP transistors do you have, say 25Vce or higher, Ic= 100mA or higher.
Need 4 for Digit drivers.

E

 

[mvs sarma]

i hope that bigal has taken care of reverse mounting the minutes displays?

 

[bigal_scorpio]

Hi Al,
Which type of PNP transistors do you have, say 25Vce or higher, Ic= 100mA or higher.
Need 4 for Digit drivers.

E

Hi Eric,

I have loads of 2N3906 which are 40v 200mA, they should be ok?

Al