Powering Pic16F84A

[paparts]

I have just finished a project using PIC16F84A micro. my project runs using computer power supply of 5 volts. but when I used 4 pcs. 1.5V battery the project don't work properly. I tried this site (http://www.talkingelectronics.com/html/Powering-A-Project.html) but it doesnt work. Can you help me how I will do it?

 

[ericgibbs]

I have just finished a project using PIC16F84A micro. my project runs using computer power supply of 5 volts. but when I used 4 pcs. 1.5V battery the project don't work properly. I tried this site (http://www.talkingelectronics.com/html/Powering-A-Project.html) but it doesnt work. Can you help me how I will do it?

Which type of battery are you using? standard alkaline or rechargeable and do you have a diode in battery connections>

 

[paparts]

Reowering PIC 16F84A

I' using a carbon zinc battery. I followed the 6 to ~5.3v conversion given by the poptronics site. I used the 1N4002 diode.

 

[donniedj]

Remove the PIC from the picture.

1. Measure the voltage of each cell.
2. Measure the voltage of the combined cells.
3. Connect diode and measure the combined voltage again with diode.
4. Attach a resistive load which will draw equal amounts of current expected from the PIC.
5. If you have a scope, monitory any ripples.
6. If resistive load pulls desired current and battery supply maintains proper voltage and ripple, then you can now scratch the new supply off the list of faults.

Swap PIC in question with another known good.
Get back to me when these are done.

 

[paparts]

Re:

Does the type of battery matter? whether it is an alkaline or a carbon zinc?

 

[Nigel Goodwin]

Does the type of battery matter? whether it is an alkaline or a carbon zinc?

Only in that normal batteries are crap! - they don't last long under any sort of load, and under a heavy load may drop too low to use.

 

[paparts]

Re:

What if I'l get less of 5.5V with the battery ? Does current matter? How do I measure the ripples? What I have here is just a multitester.

 

[Nigel Goodwin]

What are you feeding from the battery?, and presumably you've got an electrolytic across it?.

 

[ericgibbs]

I have just finished a project using PIC16F84A micro. my project runs using computer power supply of 5 volts. but when I used 4 pcs. 1.5V battery the project don't work properly. I tried this site (http://www.talkingelectronics.com/html/Powering-A-Project.html) but it doesnt work. Can you help me how I will do it?

hi,
Its just possible that the problems are not caused by the battery supply.

As we have no circuit to guide us, do you have any decoupling capacitors on the circuit board??

Is the battery/power supply, powering other devices in addition to the F84 PIC?

Do you have a PIC reset switch for the PIC? and/or a switch from the battery to the PIC supply???

Can you post a circuit?

 

[paparts]

Re:

from this link(**broken link removed**) I used the 6 to 5V conversion.

 

[Nigel Goodwin]

from this link(**broken link removed**) I used the 6 to 5V conversion.

No, we need to see the rest of the circuit!

 

[ericgibbs]

from this link(**broken link removed**) I used the 6 to 5V conversion.

Did you see my questions in my last post

 

[paparts]

Re:

sorry i did not see what you post previously. Yes the battery is powering 2-LM741 for my line follower and 555 for my siren and the motor driver

 

[ericgibbs]

sorry i did not see what you post previously. Yes the battery is powering 2-LM741 for my line follower and 555 for my siren and the motor driver

OK,
Can you answer these questions?

As we have no circuit to guide us, do you have any decoupling capacitors on the circuit board??

Do you have a PIC reset switch for the PIC? and/or a switch from the battery to the PIC supply???

Can you post a circuit?

It may seem we are asking lots of questions, but without your answers we cannot give the best advice.

You may know your project, but we dont.

 

[paparts]

Re:

Here is my ckt. diagram
**broken link removed**

 

[ericgibbs]

hi paparts,
My first reaction is that circuit will not give reliable operation with 6Volt Bty pack of ZiC batteries, especially with the diode in series with the battery.

The motors must pull down the battery voltage below the safe working voltage of the PIC, also the 555 is driving an 8hm: speaker, that must be trying to draw a heavy pulse. [the spkr needs a series resistor]

You need a more heavy duty battery pack with a voltage regulator.

Thats why the project works OK on a bench power supply.

 

[blueroomelectronics]

It's similar to my Mongoose robot kit. I'm using 4xAA NiMH 2300MAh batteries and 470uf caps on both the H-Bridge (I use a CD754410) and it works fine.

 

[paparts]

re:

So what can u suggest?

 

[ericgibbs]

It's similar to my Mongoose robot kit. I'm using 4xAA NiMH 2300MAh batteries and 470uf caps on both the H-Bridge (I use a CD754410) and it works fine.

hi Bill,

The OP says he is using Zinc Carbon batteries, which have a low specification.

Paparts..
Why not try the battery type/rating that Bill uses, it should be fairly easy to substitute NiMH for Zinc batteries.
Also add the bridge capacitors.

 

[paparts]

Re:

Can I ask for the diagram? I could not find the specs of CD754410