EQ / spectrum analizer revisited

[MrDEB]

seeing how the TL074's are duel supply can I use a single supply for the 4066 (I guess not seeing how -12v is lower than 0v )
Solution? use the duel supply for powering the 4066? instead of using a separate duel 9+/0/9- supply for the 4066 (cd4066 Vcc is max at 15v I think, need to recheck.
The 9v+ is for powering the 10 lm3916 displays.
doable hopefully?
already have the TL074's

 

[audioguru]

The input signal voltage of a CD4066 must never go beyond its power supply voltages. In your circuit, never more positive than +9V and never more negative than 0V if it has a single supply.
But the signal from the opamps goes positive and negative so the CD4066 needs a dual polarity supply.

All CD4066B ICs have a max recommended supply of 18V. They are spec'd at 5V, 10V and 15V.

 

[MrDEB]

Well back to the drawing board to add a negative voltage 9v regulator. The positive 9v regulator feeds a 2n3055 for increased amperage to power the displays. Hopefully it won't be a problem?
will post schematic after I research and add another regulator.

 

[MrDEB]

stupid idea maybe?

or use zener diodes?
power the cd4066 off the duel rail 12v supply?
the 2n3055 is to power the 3916 displays so higher current requirements

 

[audioguru]

Your 18V-0-18V transformer produces rectified and filtered plus and minus 23.5VDC (a total of 47VDC) which is much too high.
The CD4066 ICs will probably blow up with a total supply as high as 22V.

The 2N3055 transistor will produce an output of 7.5V to 8V which is not 9V.

 

[MrDEB]

Now I am confused. The 9v+ 2n3055 circuit is based on this schematic.
How to build High Current Power Supply - circuit diagram
at 7.5 to 8v is still doable to drive the lm3916 displays but what to use to power the 4066?
USE the duel rail +12/0/-12 supply and go with a lower voltage transformer?

 

[audioguru]

The 2N3055 transistor has +9V on its base. Then it will have only +7.5V to +8.0V on its emitter.
You are feeding +23.5V to the collector of the 2N3055 transistor so it will be extremely hot. Its heating is the voltage across it times the current through it.

You are using CD4066 ICs that have a max voltage of 18V. So use 15V. You can make plus and minus 7.5V with an LM317 positive adjustable regulator and an LM337 negative adjustable regulator. plus and minus 7.5V can power the opamps and the CD4066 ICs.

You need at least 11VDC to feed the 9V regulator. A 9V-0-9V transformer makes rectified and filtered plus and minus 11VDC. The 11VDC can feed the 7809, LM317 and LM337 regulators and the collector of the 2N3055 transistor.

 

[MrDEB]

hope this is right?

Re read your last post and think this is what your talking about
R2 & R4 are supposed to be 1200ohm for 7.5 volts
WHY D5 & D6?
found on web.

 

[audioguru]

The datasheet for the LM317 is also the same for the more expensive LM117 that has better spec's. Almost every schematic in the datasheet shows a circuit for the more expensive LM117 that uses a 240 ohm resistor from the output to the ADJ pin. But the LM317 uses a 120 ohm resistor instead. If a 240 ohm resistor is used with an LM317 then the output voltage will rise if the load current is low "for some ICs".
It says so in the datasheet but many LM317 projects on the web make the mistake. The same applies to the LM337 and the more expensive LM137.
Then the other resistors also should be halved. If they are 620 ohms then the output voltages will be 7.7V.

Your schermatic is missing the very important wires from the ADJ pin to the junction of the two resistors.

Your diodes D6 and D7 are needed only when the output voltage is 25V or more, there is a big capacitor at the output and the input is shorted to ground. So they are not needed in your circuit. The big capacitors C7 and C8 in your circuit are also not needed since the regulator regulates and smooths the voltage. They would be used if a high current item at the output turns on and off and produces voltage spikes.
You also do not need C5 and C6. They reduce ripple from the power input when reduced ripple is needed. The power supply pins of opamps are not sensitive to power supply ripple.

Your schematic shows a current-boosting PNP transistor for the 7809 regulator but you incorrectly label the transistor as a 2N3055 that is NPN. Label it MJ2955.

Your schematic shows a 12V-0-12V transformer that produces rectified and filtered plus and minus 15V which is good for the current-boosted 7809 regulator.

 

[MrDEB]

revisions made

so this should work pretty good.
THANKS as always your knowledge is very helpful
Now to redesign the board.
find a suitable transformer
revise the original schematic (cut/paste from this attachment.
Figure out transformer size, thinking a 2-3 amp should be big enough?

 

[audioguru]

In today's schematic, the values of R1, R2, R3 and R4 are still wrong and need to be changed to 120 ohms and 620 ohms. C5 and C6 still need to be removed.
I just noticed that the value of C1 is far too small for a medium-current power supply. 220uF is good for a current of only 70mA. Use 2200uf for a current of 700mA. Use 4700uF for a current of 1.5A. Use 10,000uF for a current of 3.2A.

I don't remember how many LEDs will be turned on at the same time but if their total continuous current is 1.5A then the transformer should be 2A.

I just noticed that the value for C9 and C10 have an unusual and hard to find value of 0.56uF. Use a standard value of 0.33uF.

 

[MrDEB]

When I went to bed after posting last night I recalled I forgot to change R!, R2, R3, R4
will make other changes as suggested.

 

[MrDEB]

corrections and pcboard

the pc board traces are all .050 in width.
Thinking the R5 should be at least 2watt
have 10 lm3916 display drivers with 10 leds per see attached
I am pretty sure we discussed this about 2 years ago?? should work??

 

[audioguru]

100 LEDs at 25mA each is a total of 2.5A.

600 ohms is not a standard value so I used 620 ohms for R2 and R3.

C2 can be a little 220uF because the negative supply has a very low current.

You have the input and output pin numbers backwards on the LM337.

 

[MrDEB]

R3 and R4 are reversed as well
Rechecked the data sheet on the lm337 - your correct on being backwards-corrected
maybe a larger resistor for the common on the led displays?
have seen the lm3916s on 12v w/o a resistor?
will figure 15ma per led x 100 = 1500ma or 1.5 A. Going with a safety factor and figure for 2A
The 9v supply if I am correct should be good for up to 5A?
need a bigger transformer and check specs on traces carrying 2A

 

[audioguru]

With a 9V supply, the LM3916 set for bar mode, all 10 LEDs lighted at 15mA each and 1.8V red LEDs then the total current is 150mA. Each output of the LM3916 has 7.2V across it so the total dissipation of the LM3916 is (150mA x 7.2V=) 1.08W so it will be extremely hot. Its max allowed dissipation is 1.365W for the DIP package.

Your 15 ohm common resistor for each display dissipates (150mA squared x 15=) 0.34W so the LM3916 dissipates (1.08W - 0.34W=) 0.74W which is still pretty hot.
If the common resistor value is changed to 27 ohms then it dissipates 0.61W (use a 1W resistor) and the LM3916 dissipates only 0.47W.

 

[MrDEB]

Revised schematic

Still need to change the common resistor to 27 ohm at 2w resistors.
made changes to caps (that 4700uf has 10mm lead spacing!, one big cap) corrected the R3 & R4
took out several caps
hopefully this is right.
It amazes me as to how you compute cap values??
revamping the display pcboards. Amazing how much neater they are after reading about proper pc board layout