Hello ,New member here,from the UK and i'm struggling with a problem .
What i plan on doing is using the circuit to switch modes on a device ,3 modes in total.the device is supplying all power needs 5Vcc (It also has a 9VCC supply if need ,but it isn't)The first two modes are controlled only by the first ne555n.
Mode 1 is activated when it receives a logic high (3 to 5 Vcc) and is kept at logic high,making mode 2 deactivated.
Mode 2 is activated when it receives a logic low and is kept at logic low.making mode 1 deactivated,Both can be toggled while the device is running .
Mode 3 is using the first 555's output to control the second 555's bistable output and keep it locked to a logic level after one of two events that happen on the device at exactly powering on the device,or about a second after the device is switched on.
The first two LEDs will be replaced with a bi or tri colour LED,to indicate which mode (1 or 2)is activated ,LED 2 (indicating mode 3)on the diagram may not be part of the final product because of how mode 3 works.
Mode 3 itself has two states,which are activated very awkwardly .e.g
When the device is powered on and in a low state (which is how the second 555 starts up with the help of a POR ),the device selects a mode to use and keeps this mode until power is switched off,but it then needs a permanent high state about a second after to operate as normal .
But to get this other mode (mode 4 in reality),the device is powered on and it gets a high state at the same time and is left in this high state to operate (hence the bistable).
So trying to have a LED colour linked to what mode (3/4 )is on, won't work easily ,so i'll probably remove it.Mode 1/2 is easy enough though and that's problem one of two.
The second problem is my main problem.
It's the switch which is to activate the modes.I'm using a momentary push button while the circuit is on my breadboard,but i want to use the momentary switch on the device and it's an old type,i think it's called a leaf switch,two long strips of metal which are apart ,then pressed together to activate it.
In it's NO state ,one side is connected to 5Vcc and when closed it is connected to 0Vss and sends this signal to an IC to reset the device.
So far i haven't been able to work out how i can use this leaf switch in place of the one on my breadboard.Only by cutting the leaf switche's 0Vss trace to the device's IC and using the Vss from the output of the 555 as a reset signal works thus far,but i'd prefer to not cut the trace ,just incorporate the leaf switch somehow.
Or i could just keep the two 555s seperate ,and use one with each leaf switch ,as the device has two leaf switches ,one is the reset and the other is a pause button which has a 4k7 pullup resistor .If i use this method i would like to try and have the reset button activate the first 555 when this leaf switch is held closed for one or two seconds,but reset would work as normal,immediately .
I also have a few SN74HC74 ICs if those are usable?
Also ,are there any improvements that could be made to my diagram,all help and advice is gratefully welcome.
This is a link to a schematic for the device i'm using .IC 315-5216 is connected to the reset switch and IC 315-5124 shows how the pause button is connected.
http://emudocs.org/Master System/master.gif
What i plan on doing is using the circuit to switch modes on a device ,3 modes in total.the device is supplying all power needs 5Vcc (It also has a 9VCC supply if need ,but it isn't)The first two modes are controlled only by the first ne555n.
Mode 1 is activated when it receives a logic high (3 to 5 Vcc) and is kept at logic high,making mode 2 deactivated.
Mode 2 is activated when it receives a logic low and is kept at logic low.making mode 1 deactivated,Both can be toggled while the device is running .
Mode 3 is using the first 555's output to control the second 555's bistable output and keep it locked to a logic level after one of two events that happen on the device at exactly powering on the device,or about a second after the device is switched on.
The first two LEDs will be replaced with a bi or tri colour LED,to indicate which mode (1 or 2)is activated ,LED 2 (indicating mode 3)on the diagram may not be part of the final product because of how mode 3 works.
Mode 3 itself has two states,which are activated very awkwardly .e.g
When the device is powered on and in a low state (which is how the second 555 starts up with the help of a POR ),the device selects a mode to use and keeps this mode until power is switched off,but it then needs a permanent high state about a second after to operate as normal .
But to get this other mode (mode 4 in reality),the device is powered on and it gets a high state at the same time and is left in this high state to operate (hence the bistable).
So trying to have a LED colour linked to what mode (3/4 )is on, won't work easily ,so i'll probably remove it.Mode 1/2 is easy enough though and that's problem one of two.
The second problem is my main problem.
It's the switch which is to activate the modes.I'm using a momentary push button while the circuit is on my breadboard,but i want to use the momentary switch on the device and it's an old type,i think it's called a leaf switch,two long strips of metal which are apart ,then pressed together to activate it.
In it's NO state ,one side is connected to 5Vcc and when closed it is connected to 0Vss and sends this signal to an IC to reset the device.
So far i haven't been able to work out how i can use this leaf switch in place of the one on my breadboard.Only by cutting the leaf switche's 0Vss trace to the device's IC and using the Vss from the output of the 555 as a reset signal works thus far,but i'd prefer to not cut the trace ,just incorporate the leaf switch somehow.
Or i could just keep the two 555s seperate ,and use one with each leaf switch ,as the device has two leaf switches ,one is the reset and the other is a pause button which has a 4k7 pullup resistor .If i use this method i would like to try and have the reset button activate the first 555 when this leaf switch is held closed for one or two seconds,but reset would work as normal,immediately .
I also have a few SN74HC74 ICs if those are usable?
Also ,are there any improvements that could be made to my diagram,all help and advice is gratefully welcome.
This is a link to a schematic for the device i'm using .IC 315-5216 is connected to the reset switch and IC 315-5124 shows how the pause button is connected.
http://emudocs.org/Master System/master.gif
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