Could use some help please

Discussion in 'The Projects Forum' started by kurtruk, Aug 26, 2012.

  1. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
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    Hello, as you may know I am new here and I have little knowledge of electronics as I am learning. Could you take a look at this schematic and see if you see anything wrong with it. I am especially concerned with the current. Do I have enough? What about all the Vccs of the ics?
    Here are the links of the parts used

    And Gates
    http://www.digikey.com/product-detail/en/SN74AHC08N/296-4524-5-ND/375858

    LEDhttp://www.digikey.com/product-detail/en/WP3A8GD/754-1217-ND/1747616

    Transformer
    http://www.digikey.com/product-detail/en/FS10-250/237-1031-ND/242476

    Bridge Rectifier
    http://www.digikey.com/product-detail/en/W01G/W01GDI-ND/278871

    Voltage Regulator
    http://www.digikey.com/product-detail/en/NCP553SQ30T1G/NCP553SQ30T1GOSCT-ND/3487600

    Crystal Oscillator
    http://www.digikey.com/product-detail/en/TC32N5I32K7680/CTX1184CT-ND/3511743

    4520
    http://www.digikey.com/product-detail/en/M74HC4520B1R/1026-M74HC4520B1R-CHP/2521285

    Display
    http://www.digikey.com/product-detail/en/LDD-HTC512RI/67-2098-5-ND/2239251

    4511
    http://www.digikey.com/product-detail/en/CD74HC4511E/296-14537-5-ND/555825

    I think that is it except for more ordinary parts like resistors and capacitors
    Any help at all would be appreciated please explain thoroughly as I am new to this. Note: any labels are what i think will happen not necessarily what will.
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
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    You need to post your schematic as a .PNG or .GIF file.
     
  3. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    i guess specifically my Qs about current is how much mA (current) should i apply to high inputs such as enable pins and how much current should i apply to Vcc of each Ic?
     
  4. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    just a second wrong one
     
  5. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    ok this should be it sorry about that
     
  6. Audioguru

    New Member

    Dec 20, 2007
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    If the power supply for the CD4511 is only 3V then its voltage drop of 1V to 1.5V will not allow it to light LEDs that need 1.8V to 3.6V.
     
  7. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    Ok for future reference how do I calculate that voltage drop and what about current on pins that need to be high and how much current should I suplly to Vcc pins of each ic
     
  8. Audioguru

    New Member

    Dec 20, 2007
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    The datasheet for the CD4511 shows its typical voltage drop vs output current. The max allowed output current is 25mA per output.
    The datasheet for the LED display shows its range of forward voltage and its maximum allowed current per segment.

    You do not supply current to the IC, instead you supply voltage. Then the IC takes as much current as it needs. If you do not use current-limiting resistors for each segment of the display (as shown in the datasheet for the CD4511) then the ICs and LEDs might blow up. Use Ohm's Law to calculate the voltage drop of the current-limiting resistors.
     
  9. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    each of the resistors in between the 7 segment are 100 Ohm
    does everything look okay for this the net running through the origin of each part would be the Vcc

    Name Amount $ each $ total datasheet digikeylink
    AC Chord
    http://www.assmann.us/specs/AK500-OE-7-1-R.pdf http://www.digikey.com/product-detail/en/AK500-OE-7-1-R/AE10696-ND/2504538

    Transfromer
    http://system.netsuite.com/core/media/media.nl?id=5816&c=ACCT126831&h=7de295966eceb2cdb483&_xt=.pdf http://www.digikey.com/product-detail/en/VPP10-1000/237-1053-ND/242497

    Bridge Recitifier
    http://www.diodes.com/datasheets/ds21202.pdf http://www.digikey.com/product-detail/en/W01G/W01GDI-ND/278871

    Capicator
    http://www.chemi-con.co.jp/e/catalog/pdf/al-e/al-sepa-e/004-lead/al-ky-e-110701.pdf http://www.digikey.com/product-detail/en/EKY-100ELL102MJ16S/565-1504-ND/756020

    Regulator http://media.digikey.com/pdf/Data Sheets/Toshiba PDFs/TA78xxSB.pdf http://www.digikey.com/product-detail/en/TA7805SB(TP,Q)/TA7805SB(TPQ)CT-ND/2264622

    Resistor
    http://industrial.panasonic.com/www-data/pdf/AOA0000/AOA0000CE28.pdf http://www.digikey.com/product-detail/en/ERD-S2TJ132V/P1.3KBACT-ND/503610

    Crystal http://media.digikey.com/pdf/Data Sheets/CTS Corporation PDFs/Model TC32.pdf http://www.digikey.com/product-detail/en/TC32N5I32K7680/CTX1184CT-ND/3511743

    Transistor
    http://www.fairchildsemi.com/ds/2N/2N5551.pdf http://www.digikey.com/product-detail/en/2N5551YBU/2N5551YBU-ND/975303

    4520 http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00002544.pdf http://www.digikey.com/product-detail/en/M74HC4520B1R/1026-M74HC4520B1R-CHP/2521285

    4511
    http://www.ti.com/lit/ds/symlink/cd4511b.pdf http://www.digikey.com/product-detail/en/CD4511BE/296-2072-5-ND/67341

    LED http://www.us.kingbright.com/images/catalog/SPEC/WP3A8GD.pdf http://www.digikey.com/product-detail/en/WP3A8GD/754-1217-ND/1747616

    AND
    http://www.ti.com/lit/ds/symlink/sn74ahc08.pdf http://www.digikey.com/product-detail/en/SN74AHC08N/296-4524-5-ND/375858

    Display http://media.digikey.com/pdf/Data Sheets/Lumex PDFs/QuasarBrite High Temp LED Displays.pdf http://www.digikey.com/product-detail/en/LDD-HTC512RI/67-2098-5-ND/2239251

    Resistor 100 ohm
    http://www.seielect.com/catalog/SEI-CF_CFM.pdf http://www.digikey.com/product-detail/en/CF14JT100R/CF14JT100RCT-ND/1830327
     
  10. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Go back into Eagle, and click Erc. You'll get a lot of error messages, as you haven't provided nodes VDD and VSS for the 4000 series ICs, and you have multiple outputs tied together which is a no-no.
    Use Erc early, and use it often. If you have any "Errors", you shouldn't try to create a PCB, or they won't be in sync - which is a real mess.
    Use some of the symbols in Supply1.lbr or Supply2.lbr to add GND, VDD, VSS, etc to your schematic.
    Alternatively, you could use the INVOKE command (looks like four AND gates on the left menu bar) and then click on each IC and select the "Request" entries (gate:p) to display the VDD/VSS/VCC/GND pins.

    You should be using a 4000 series quad AND gate instead of the 74HC. A 4081 will do it for you.

    The NPN transistor is wired as an emitter follower, but the collector is connected to what will be GND or VSS, and the emitter has no pull-down resistor. I'm not sure what you wanted to do there.

    Your LEDs are connected backwards, and they do not have individual current limiting resistors.

    You're limiting your power supply to 3v - why? 4000 series CMOS can use from 3v to 16v; some can go to 18v.

    R1, R4, R5 and R6 will cause problems.
    You need a fuse on the primary side of the transformer.

    As far as schematic conventions; generally you have inputs on the left, and outputs towards the right. More positive voltages towards the top of the schematic, and more negative towards the bottom. For example, your ACPLUG should've been on the far left of the schematic, then a fuse, then the transformer, etc. Keeping your schematics adhering to conventions make them much easier for people to understand them quickly.
    I prefer that people use a white background for schematics, as I find them easier to read that way.
     
    Last edited: Aug 28, 2012
    Wendy and absf like this.
  11. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    First off if I'm not using those output pins then I have to run a individual net to ground? Why can't they be tied together?

    I guess I don't really understand resistors yet I'm trying to make it a switch because my crystal is limited to a max of 3mA but I thought I should have more current for the clk of the 4520s.

    I don't understand how my LEDs are backwards isn't the electron flow coming out of the regulator and into the small side of the triangle like it supposed to?

    As for the resistors why? I an thinking you are looking at the older schematic.
    As for everything else thanks a better schematic is under creation.

    Note: please tell why I can't do something otherwise I never learn knowledge I just learn facts (that's why i hate school they never tell you why ie why you can do what you do in math)
     
  12. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    Ok for unused output pins do i just do nothing or what?

    My crsytal osscilator is limited to 3mA; is my resistor right and then is the output big enough for the 4520s

    If a resistor is unlabeled then it is 100 ohm

    I don't understand how my LEDs are backwards isn't the electron flow coming out of the regulator and into the small side of the triangle like it supposed to?

    SgtWookie said i needed i fuse: fuses are new to me. I put it on the 120V side of the transformer right? how big of a fuse do i need? Do i need two one for each wire running to the transformer?

    Are there any other problems with the schematic?

    also i know i practically this clock goes SS:MM:HH but it is just laid out that way on the schematic for easy reading.

    Note it would be very helpful if you explained WHY.

    I changed my and ic from TTL to CMOS here is the new data sheet:
    http://www.digikey.com/product-detail/en/HCF4081M013TR/497-1140-1-ND/586140
     
  13. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    You're getting inputs and outputs confused. All CMOS INPUTS must have a current path to Vdd or Vss/GND, or you will have big problems. On the other hand, unused OUTPUTS should be left disconnected.

    I didn't understand them when I first started; nobody else did either.
    The inputs of 4000 series CMOS ICs are like very small capacitors; nearly infinite resistance to Vdd and Vss/GND, and once charged or discharged it takes no current to keep them in that state. Your 3mA xtal clock should be able to work just fine as a system clock for the 4000 series CMOS. Were you using 74 or 74LS TTL, you would need to buffer your oscillator.

    You're getting electron flow and conventional current flow confused, which is very easy to do.
    In this case, the regulator outputs +3v. Electron flow goes from more negative to more positive. Conventional current flow goes from more positive to more negative. We occasionally mention electron flow here, but we stick with conventional current flow to try to keep people from getting confused.

    I was looking at clock.sch that you had posted using Eagle 6.1.0. When you post a .sch or .brd file, you should also mention which version of Eagle you created the schematic or board with. A later version of Eagle can read files created by earlier versions, but once it's saved by a newer version, the older version cannot read it any longer.
    Good. :)

    I generally do try to explain why I recommend various things, because it may not be obvious to a newcomer - and learning things about electronics is one of the main reasons why the board exists. Unfortunately, I may not always have the time to explain things. You might notice it's been a good while between replies; I simply don't have as much time to spend on here as I used to.
     
  14. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Leave unused OUTPUT pins disconnected. Unused INPUTS must have a current path to Vdd or Vss/GND.

    You did not specify the reference designator for the resistor in question. The reference designator is the letter/number combination next to the component; ie: R4, C2, Q5, T1, etc.

    You should always specify a value for resistors on schematics.
    100 = 100 Ohms
    1k = 1,000 Ohms
    1M = 1,000,000 Ohms (note: in SPICE simulations, you need to use 1MEG instead of 1M)

    Think of the triangle as an arrow. The point of the arrow needs to go towards the more negative voltage.

    Yes; this protects both the project and the human in case of a fault.
    100mA to 500mA would be OK.
    No, just one in the HOT wire. You don't want to fuse the neutral nor the GND wires. With a meter set on 200VAC or higher, you should measure less than 3v between Neutral and GND, and approximately 120v between the HOT wire and either Neutral and GND. [/QUOTE]

    This is going to be an iterative process. You need to fix the existing problems first, then re-post your .sch file so we can take a look.

    BTW, I prefer using the symbols in supply2.lbr over those in supply1.lbr.

    Well, you have the schematic flip-flopped horizontally.
    You really should have it the other way. It would be easier to understand.

    OK, good.
     
  15. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The part number for your displays is for common-cathode but your schematic shows CA pins (common-anode?) with the common pins connected to the positive supply.
    The CD4511 drivers can drive only common-cathode displays.

    The common pins of common-cathode displays should be connected to 0V.
     
  16. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    This a list of what I changed

    I added a fuse here is the datasheet/info:
    fuse: http://www.digikey.com/product-detail/en/5MF 300-R/507-1258-ND/1009030
    Fuse holder: http://www.digikey.com/product-detail/en/64900001039/WK0011-ND/245470

    I changed my displays to common cathode (there were common anode just because i clicked on the wrong one)

    I changed my CC of my displays from Vdd to Vss

    I turned around my LEDs

    I switched my schematic so it went HH:MM:SS

    I changed my resistors R1-R46 to 500 Ohms

    I changed R48 to 1800 Ohms

    I think that is it.

    I posted both a .sch and a .png (.sch is in the zipped folder because it was just to big to upload it)

    I'm not 100% sure my resistor values are correct.

    Thanks for all the help without you I would just try to build it and get very frustrated.
     
  17. Audioguru

    New Member

    Dec 20, 2007
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    Using the very low supply voltage of 5V and the very high value 500 ohm resistors to limit the current in the displays to about only 4mA then the displays will look very dim.
     
  18. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    Ok so I know V=IR so why wouldn't 5=x500 so you divide both side by 500 and get 0.01 or 10mA what am I missing?
     
  19. Audioguru

    New Member

    Dec 20, 2007
    9,411
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    The 5V is not across the resistor producing 10mA.
    The 5V is divided across the LED in the display (maybe 2.0V or more for a green display) and 1V or more is lost in the output of the CD4511 so only 2V or less is across the 500 ohm resistor producing only 4mA or less.

    Your schematic is as big as my neighbourhood because its parts are too far apart.
     
  20. kurtruk

    Thread Starter Member

    Aug 26, 2012
    140
    6
    wow your neighborhood must be pretty small jk

    so I Should have 200 ohm 2/200=10mA?
     
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