HELP WITH THE CD4029 BCD/DECADE UP/DOWN COUNTER

[madauzz]

Any one can help me on how to operate this thing correctly?? I want it to count in BCD/UP. I tried to test it and connecting it as ff: (pin 16=9v(Vdd); pin 15=input from a dc supply (3v) with spdt switch; pin 13&12=gnd; pin 10&9= Vdd; pin 8=gnd; pin 5= gnd; pin 3&4=gnd; pin 1=gnd..) Need Reply ASAP!! Im using this in my robot project...

 

[mcs51mc]

Did you read the datasheet correctly :?: :?: I don't think so :evil:

Pin 1 is the clock (count) input so connecting it to ground :?: :evil:
Pin 15 is the reset input. Connect it to VDD to reset the counter or to GND when you want to count. But never to something like 3V :?: :evil:

I didn't look further, please check the datasheet first and come back if it still doesn't work.

 

[madauzz]

Sorry

im sorry it's not cd4026 but cd4029 presetable bcd/decade up/down counter. i read the specifications from fairchild and connected them the configuration above... can you help me with that???

 

[mcs51mc]

Connections looks good for the 4029
But what about your clock input? Still 3V ? :evil:
If your Vdd= 9V then the clock should be 0 or 9V :!:
Everything in between is cause of problems.

Thake a good look at the datasheet "DC Electrical Characteristics" and you will find out what the appropriate levels are (VIL & VHL).

Good luck

 

[madauzz]

thanks

ive already made it work just a while ago.. thanks for the tip. yet, i still have one more problem. my problem is with cd4013 (d-flipflop).. i dont know if this thing do latching. but if it does. can you help me connecting it so that it will funcion as: when i trigger it high Q would be high and latch so that when no trigger voltage is applied Q would still be binary 1 then when i trigger it again it will go low.? i already have a prinout of the specs from fairchild but still i dont know how to make it work like i wanted it to.. im still a student. i have to admit that im still a newbie in the practical (hands-on) field.. i want to enhance my skill and know more.. any help would be highly appreciated.

 

[mcs51mc]

I'm sure you've already make it work but to be sure:
R=S=low // D=not Q // With every clock Q wil invert

 

[madauzz]

thanks again!

yet still this project is giving me a hard time.. no problems with 4029 and 4013. i used the 4029 counter to count pulses from a motor; which i used an IR transmitter and receiver. the receiver generates the pulses for the counter. the counter is connected to a control circuit which has a high output for 1-8 pulses. the controller is connected to an amplifier. i used 2n3904. the problem now is that the current from the controller is too small to drive the transistor. 2n3904 needs at least 100mA current through the base in order to drive the motor. what should i do to amplify the current from the control circuit? i tried cascading as much as 5 2n3904s yet not enough. it only amplifies from 10nA to 1uA. Even if i add another transistor the amplified current stays at 1uA. Any suggestions?..

 

[Nigel Goodwin]

I suggest you try posting your circuit! - you're doing something badly wrong if five transistors aren't giving you enough gain!.

Assuming each has a gain of 100?, that gives a total gain of 10,000,000,000 - which is 'quite a lot'.

 

[madauzz]

Here's a simple circuit diagram.. the sensor goes high each time it's unblocked. i tried simulating the transistors alone using multisim. the current after adding upto 4 the current starts to decrease..

 

[mcs51mc]

Long time ago that I designed a transistor circuit so Nigel will correct me if I'm wrong :?

I think the following things has to be changed:
1) motor on collector side of transisitor not on emitter side (how do you expect the transistor to go in saturation with an unknown base current and Vbe voltage?)
2) you need a resistor between the output of the FF and the transistor base to set a base current.
3) if your motor needs 100mA to turn I think the 2N3904 is not the good choice. Ic max is 100mA. But give it a try and you will see if it's heating up.

From the datasheet of the 2N3904:
hfe @ (Ic=100mA) = 30
Vbe saturation= 0.7V

Let say you need 100mA of Ic then you need a base current of 100/30=3.33mA
The FF outputs 6V with a "1" output so you need a base resisitor of (6-0.7)/3.33= 1.6kOhm
Basic transistor calculations :wink:

Try these modifications and see what you get

 

[Nigel Goodwin]

Sorry to be negative :cry:

But there's nothing right about that circuit at all, it's also hard to really know what you're doing, as (I'm presuming?) you've only shown a small number of the components. 'mcs51mc' is right in his comments, you're driving the motor completely wrong, you need a much better transistor to drive the motor, you need a protection diode across it, and the motor needs to be in the collector of the transistor. Connecting an IR transmitter (which is rather vague?) to the motor isn't a good idea either!.

 

[madauzz]

i know..

i know.. the design itself is quite complicated. i need the motor to be in the emitter side cause i need to operate it both forward and reverse. in fact im using the transistor as a switch, using it in dc. as long as the saturation current through the base is achieved, collector and emitter will short. yes it's better if the motor was in the collector cause it won't have a minus 0.7 voltage drop in B-E. you're right about having a base resistor to adjust the base current but the trigger of the base is from combinations of AND, OR, NOR gates. The output curent from those combinations is pretty low. I assumed that the output impedance of the combinations is very high. If i put a base resistor it will make the current even lower. Im still working on it right now. Anyway, the schematic i posted earlier was simplified. No problem with the other parts of the design but the current amplification. here's the complete schematic of the motor driver. You can actually try them yourselves if you have spare transistors. It will forward and reverse the motor as long as enough Ib is apllied. The unused base should be grounded ( always = 0v). Also if you have a spare cd4081, try using all the gates of the IC and connect it on one base and you'll see what i mean (low current).

 

[madauzz]

continuation

i don't think there's anything wrong with the design cause ive tried tesing each part of the design in isolation, they where working. even the driver of the motor is working. as ive said you can try it if you have spare parts. The only problem that ive encountered, ive already said, the current from the combinations of logic gates is very low. which i need to amplify. Note: it's DC not AC. Transistors can work fine even without biasing resistors when used in DC (based on my experience). I only put resistors on the junctions if i need to limit the current to avoid burning it. what i need is to amplify the current enough to shorten C and E.

 

[Nigel Goodwin]

Re: continuation

i don't think there's anything wrong with the design cause ive tried tesing each part of the design in isolation, they where working. even the driver of the motor is working. as ive said you can try it if you have spare parts. The only problem that ive encountered, ive already said, the current from the combinations of logic gates is very low. which i need to amplify. Note: it's DC not AC. Transistors can work fine even without biasing resistors when used in DC (based on my experience). I only put resistors on the junctions if i need to limit the current to avoid burning it. what i need is to amplify the current enough to shorten C and E.

As we've all said previously, you need the motor fed from the collectors, you didn't mention before that it was for an H-bridge - but it doesn't really make any difference - you still need the collectors feeding the motor. As it stands you're getting 0.7V drop across every transistor - so in your latest diagram you're losing at least 2.8V out of your 6V supply!.

Also your output transistors are far too small for the job, 100mA transistors have no place driving motors!. Check the Cybot motor driver board at my website , the output transistors are rated at 2A, but even at that you mustn't use rechargeable batteries - as stall current would easily blow the transistors.

 

[madauzz]

Geez!!

Geez Nigel!! You really are a God! Ok im going to modify the circuit again.. thanks to your sight. It gave me new ideas..