CRITISIZE THESE CIRCUITS

[alabimusty]

Hi Folks,

I posted sometimes ago that I needed a circuit for a ‘remote ceiling fan remote control regulator’. Thanks to NURA that gave me an explanation on that but could not draw the circuit, perhaps, due to time constraints. I have been so busy myself, but I had to squeeze time to design these circuits, which is now posted for your criticism.

I prefer 4518 and 4511 to 4026 based on my survey. I have also generated a pulse of 0.11s from the 555 timer IC. I want your advice based on wealth of knowledge on the functionality of this circuit, especially, the value and connection of the active and passive components.

I want your explanation on the Mickey Mouse AND gate operation i.e. the value of the resistor, the two diode values, calculations and principle of operation. Also, I want simulation software. I tried Circuit Maker 2000 but no success.

Please, help me with all ASAP.

Musty

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[alabimusty]

This is the last part of the circuit diagram

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[alabimusty]

I have been waiting for your response folks, please, reply

 

[ante1]

Hi Musty,

Why not assemble it on a proto-board for a test drive?

 

[audioguru2]

Hi Musty,
The 4A fuse following the regulator is way too high. It isn't needed anyway since the regulator will current-limit if the current reaches 1A to 2.2A, and shut-down if it gets too hot.
The resistance of the fuse ruins the voltage regulation.
The regulator doesn't need the huge capacitor at its output. 0.1uF to 10uF will be fine.

The 555 monostable won't work with its pins 6 and 7 shorted to ground.

View attachment 38282

 

[alabimusty]

Hi Ante, I have tried it on a breadboard but it seems there is no transmission from the transmitter and I can not ascertain the behaviour of the receiver from this.

Hi Audioguru, I absolutely agreed with you on the power supply unit and for the monostable circuit, I made a  mistake with C3, its actually attached to the pin 6 and 7 after R5 before connecting to ground and not on pin 1. Pin 1 is direcly connected to the ground. What I am not sure about is the connection of pin 8 to both ground and Vcc, also, the reset pin 4 is not connected.

I also want your opinion on my timing circuit, that is R5 and C3.

 

[audioguru2]

Hi Musty,
Most 555 manufacturers have an error on their graph for a monostable's timing, so I looked in Signetics databook, its inventor. No graph but the same formula as everyone else: t= 1.1RC, which is 11ms. It won't time-out if the trigger pin is low just before and during time-out. ;D

 

[alabimusty]

Thank you Audioguru, Pls, I still need explanation based on request below


What I am not sure about is the connection of pin 8 to both ground and Vcc, also, the reset pin 4 is not connected.

 

[audioguru2]

Hi Musty,
Pin 8 is the 555's Vcc pin and pin 4 also connects to Vcc if you don't want a reset. Your schematic shows them correctly.
Your 555 is missing a couple of supply bypass capacitors connected very close to pins 8 and 1. The 555 has a high power output which draws a supply current spike of up to 400mA when it switches. The supply bypass capacitors hold the supply voltage up during the spikes so that nearby circuits aren't affected. The pcb traces have inductance which limits the power supply from holding the voltage up during the spikes.A 0.1uF ceramic disc capacitor is good for high frequencies and a 1uF or more electrolytic cap is good for lower frequencies of the spike. This is what National Semi recommends on their datasheet:

View attachment 38284

 

[alabimusty]

Thanks Audioguru,

So, I can attach the bypass capacitor to pin 8 before Vcc?
I also guess that pin 1 is Ok to be grounded directly.

Have you checked the connections of CD4017, CD4518, and CD4511. Pls, take a closer look at my resetting of the CD4518?

How can I actually utilize mickey mouse AND gate to achieve the resetting?

 

[audioguru2]

So, I can attach the bypass capacitor to pin 8 before Vcc?

Pin 8 is Vcc. ICs don't have a "before" and an "after", the bypass caps connect with short wires as close to pins 8 and 1 as possible.

I also guess that pin 1 is Ok to be grounded directly.

Pin 1 is ground.

Have you checked the connections of CD4017, CD4518, and CD4511. Pls, take a closer look at my resetting of the CD4518?

I didn't look in the datasheets for the pins' functions and timing for the ICs. You can do that and try the circuit to see if it works. The 4518 might have trouble resetting since its own output is used. It might make a reset pulse too short to fully reset the beast.

How can I actually utilize mickey mouse AND gate to achieve the resetting?

A Mickey Mouse AND gate is two diodes and a pull-up resistor.

 

[alabimusty]

Thanks Audioguru,

I understand everybit of it except the resetting issue at 4518, what could be the solution? Pls, look through the transmitter?

However, I am already arranging the components for testing

Once again, thank you

 

[audioguru2]

I guess you didn't read the datasheet. The reset gate needs a pulse-stretcher.

View attachment 38287

 

[audioguru2]

Oh yeah,
Switch contacts bounce maybe 20 times for each push of the button. Your "transmitter" needs a "debounce" circuit for the pushbutton switch so it makes a single pulse to the LED.

 

[alabimusty]

Thanks Audioguru,

I have actually experience the gate problem at 4518 and I understand the necessity for a pulse-stretcher but I dont know how to design for this?

I want your opinion on the trigger pulse synchronisation between 4017 and 4518, it seems there is delay?

Once again, thanks for your responses.

 

[audioguru2]

Sorry Musty,
I haven't played with counter ICs for ages. Maybe someone else can help.

 

[alabimusty]

Thanks a lot Audioguru,
I hope somebody help me on time

 

[pwillard1]

Pulse stretching: 3 ways I've done it.

1) if the "pulse" is quick, insert a Small Capacitor like a .01uF in the path and see if it has the desired propagation effect due to capacitor charge delay.

2) Insert a Buffer IC

 

[Sukhbinder]

i suggest u use the 7555 (the cmos equivalent of the 555). i happens that when a 555 switches states, it produces a surge of about 400mA which can easily upset the timimg for the other digital circuit elements, while a 7555 has a surge of just 10mA. i yself have been woking on this circuit and have got the components but due to lack of time i have not been able to finish it. i seem to have a circuit for a pulse stretcher in my notes, maybe this can help u out

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