Hello,

The 10 Volts input voltage is the "ideal" situation.
With 12 Volts input the circuit will still work fine.
There only will be some more heat generated.
You will probably need a bit larger heatsink.

As for the capacitors, ceramic capacitors will be fine.

Bertus

 

Hello,

The 10 Volts input voltage is the "ideal" situation.
With 12 Volts input the circuit will still work fine.
There only will be some more heat generated.
You will probably need a bit larger heatsink.

As for the capacitors, ceramic capacitors will be fine.

Bertus

Sorry,,I'll be using a 9 volt battery for lm7805A And it take 10v input..
Datasheet recommends ci capacitor 0.33micro and 0.1micro at the output
In This case do I need another decoupling cap on the main vcc/ground rail?
And are those values for the caps good?, why at the beginning did u mention to put 100micro at the Input side of the regulator and 10micro on the output? Datasheet recommends 0.1 output and 0.33 input

 

You are being preoccupied with capacitor values. What you see and read are only recommendations.

Here is what you need to know. Capacitors are used as filters.

A high frequency filter needs a low value capacitance such as 0.1μF
A low frequency filter needs a high value capacitance such as 10-1000μF

A voltage regulator such as LM7805 needs a high frequency filter at the input and output pins to prevent oscillation. So we put a 0.1μF cap at the input and output pins to GND.

Both analog and digital circuits generate and are sensitive to high frequency noise, hence we put 0.1μF caps between Vcc and GND pins at every chip.

Large switching currents drawn by such things as LEDs need a reservoir capacitor. Hence we put 10-100μF between Vcc and GND especially when the supply line from the regulator is long distance away (inches).

Similarly, the supply from the battery may sag under heavy load. Hence we put 100-1000μF from the output of a rectifier or battery to smooth out the supply voltage.

Pay attention to these recommendations if you want reliable operation.

 

Sorry,,I'll be using a 9 volt battery for lm7805A And it take 10v input..
Datasheet recommends ci capacitor 0.33micro and 0.1micro at the output
In This case do I need another decoupling cap on the main vcc/ground rail?
And are those values for the caps good?, why at the beginning did u mention to put 100micro at the Input side of the regulator and 10micro on the output? Datasheet recommends 0.1 output and 0.33 input

Why? Because your circuit was constructed on breadboard and your connections are too long, plus you're using the old TTL chips which consume heavy currents.

If you're using PIC microcontrollers or CMOS 4000/74HC series of chips and if you've designed a proper PCB for your circuit, you might be able to follow the recommendations on the datasheet.

Allen

 

The 0.33uf input capacitor and the 0.1uF output capacitor at the pins of the LM7805 are ceramic and prevent the regulator from oscillating. These capacitor values are used when the input voltage is 7V to 25V.
Page 12 of the datasheet is for the more expensive LM7895A but an ordinary LM7805 will work for powering your circuit (see page 3 of Fairchild's datasheet).
The input of the regulator also needs a huge filter capacitor from the bridge rectifier.

Your digital circuit board should have one 10uF cap for the entire circuit plus one 0.1uF cap as a supply decoupling cap for each old TTL IC.

 

The 0.33uf input capacitor and the 0.1uF output capacitor at the pins of the LM7805 are ceramic and prevent the regulator from oscillating. These capacitor values are used when the input voltage is 7V to 25V.
Page 12 of the datasheet is for the more expensive LM7895A but an ordinary LM7805 will work for powering your circuit (see page 3 of Fairchild's datasheet).
The input of the regulator also needs a huge filter capacitor from the bridge rectifier.

Your digital circuit board should have one 10uF cap for the entire circuit plus one 0.1uF cap as a supply decoupling cap for each old TTL IC.

i am using ls series gates..take a look at the picture attacked..this is the final connection for my caps(0.33 for the input of the reg 0.1for tye output of the reg 5v side; 0.1 for each ttl and 2 100micro for each vcc/ground rail for each board) ..correct me and what do you think? so we can resolve the problem and close the case..regards

 

I'll be using a 9 volt battery for lm7805A And it take 10v input.

Did you look at the datasheet of a puny little 9V alkaline battery to see how low its output current is and the very short duration it might work driving these old very high current TTL ICs? Did you see how quickly its voltage drops below 7V when the ordinary 5V regulator WILL NOT WORK?
That is why I recommended using seven AA alkaline cells to make 10.5V when new and 7V when old at a current and duration 5 times more than a 9V alkaline battery.

Did you look at the datasheet of each old TTL IC to see their very high supply current required?

Maximum supply current:
7414= 60mA
7486= 40mA x 4= 160mA
7447= 103mA
74283= 110mA
8 LEDs in the display= 80mA

The total maximum current is 513mA but might be half at 257mA.
A brand new 9V alkaline battery voltage will drop to 7V in about 8 minutes or 24 minutes.

 

Are the caps position good?(correct me if i'm wrong,see previous post)answer me before talking about the battery.Please let's talk and solve problems step by step not by mixing All ideas together. Regards. I'll try to economize the battery for the longest time available

 

Are the caps position good?(correct me if i'm wrong,see previous post

Yes you have most of the capacitors and placed them correctly except:
1) You should have a pretty big capacitor parallel to the battery becaues its load current will be very high and a battery might have trouble with high load current spikes. Maybe 1000uF.
2) The polarity of the electrolytic 100uF capacitors is not shown.

 

Yes you have most of the capacitors and placed them correctly except:
1) You should have a pretty big capacitor parallel to the battery becaues its load current will be very high and a battery might have trouble with high load current spikes. Maybe 1000uF.

So you are advising me putting a 1000micro instead of the 100micro near the regulator or directly in palarell of the 0.33?
do i need to keep both 100micro?Must the 1000micro be electrolytic polarized?
Regards

 

Do you understand that 1000μF in parallel with 0.33μF is not simply 1000.33μF?

You will not be able to find a 1000μF capacitor that is not electrolytic polarized.

 

Do you understand that 1000μF in parallel with 0.33μF is not simply 1000.33μF?

You will not be able to find a 1000μF capacitor that is not electrolytic polarized.

Yes I know that connecting the 1000micro in parallel with .33miro will not make it 1000.33micro..where do I need to connect the 1000micro? (do I need to replace the 100micro near the regulator by the 1000micro?)

 

So you are advising me putting a 1000micro instead of the 100micro near the regulator or directly in palarell of the 0.33?
Do i need to keep both 100micro?
Must the 1000micro be electrolytic polarized?

Read my peply #49 again. I said to connect a huge capacitor parallel with the battery which is the input of the regulator that also has the 0.33uf ceramic capacitor. The OUTPUT of the regulator has the 0.1uF ceramic and the 100uF capacitors, not the input of the regulator.

 

I didn't find a 0.33micro for the input of the reg is it okay?
Regards

 

I didn't find a 0.33micro for the input of the reg is it okay?

It is not OK if the regulator oscillates.
ALL manufacturers of 7805 regulators recommend 0.33uF so use 0.33uF.
EVERY electronics parts distributor (not RadioShack) has a 0.33uF ceramic capacitor.

If you connect a 0.1uf parallel with a 0.22uF then you get 0.32uF. Both should be ceramic.

 

Why do you think it is too big?

Never mind the quote..now the circuit is working properly 100% when 8 people are out only "8" led is on and everything except the regulator is good.. I connected in the input(9v side) one 0.1 micro at the output 5 regulated side iv'e connected the common ground on the regulator to the rest of the circuit and the +5 v regulated to the rest of the boards..Iv'e also connected a 1000 micro cap on the Board where the regulator is located in and as close as possible to the reg. finally I've connected the 9 v battery the + on the input and the- on the common ground of the reg..the circuit lighted up..but the lamps are so Weak..Iv tried to input the switches nothing happens..I've tried many things (2 0.1 caps on the 9v input/ the 1000micro cap on the 9v input tried also the regulator alone without any cap with it but SAME RESULTS ALWAYS) help me
It's a 7805c reg

 

Measure the input voltage to the regulator and its output voltage when the circuit is lighting some LEDs and tell us what the voltages are.

Old 74xx TTL ICs are not designed to light LEDs when their output is high. The logic high voltage from a TTL output that is overloaded by an LED might not be high enough for a digital circuit to work.

 

Measure the input voltage to the regulator and its output voltage when the circuit is lighting some LEDs and tell us what the voltages are.

Old 74xx TTL ICs are not designed to light LEDs when their output is high. The logic high voltage from a TTL output that is overloaded by an LED might not be high enough for a digital circuit to work.

A problem encounters :s I dont have a voltmeter, however the circuit without the regulator with 6v supply is working 200% fluently. I tried the regulator with a single led and the led's light is not powerful it barely light

 

A digital voltmeter costs as low as $10.00. Get one.
A 7805 regulator turns itself off when it gets too hot, or maybe you connected its pins backwards.
A little 9V battery is too small to power your high current circuit. I think your little 9V battery is dead.

 

A digital voltmeter costs as low as $10.00. Get one.
A 7805 regulator turns itself off when it gets too hot, or maybe you connected its pins backwards.
A little 9V battery is too small to power your high current circuit. I think your little 9V battery is dead.

I am lighting my circuit with the 6v pack I barely used the 9 volt..I'll show u some simulation of the circuit and the intensity of a single led using my regulator