Hi everybody, I need help with the following.
I have assembled the following circuit (Fig 1), originally obtained from:- https://www.twovolt.com/2016/11/30/10-channel-chaser-mosfets-output-driver-using-lm555-cd4017/
The only difference being R4 to R13 which are 470R because I did not have any 100R resistors at the time of assembly.
It is however working well and flashes sequentially from Q0 through to Q9.
I would like to change the flash pattern by using some 1N4148 diodes as in so many other similar circuits that may be found on the net. (ie. Fig 2)
I always make very small changes/additions/modifications to existing circuits because it is easier for me to see if I am going in the right direction so I started off by dropping in the first 1N4148, (D1, Fig 3).
And now here is the problem that I am struggling with. The LED array 1 attached to Q1, D1, R4 remains light while the rest correctly continue to flash sequentially one by one.
When I disconnect the gate of Q1 from the D1 cathode and connect it to D1 anode (effectively removing D1), everything works correctly.
I have tried swopping the direction of D1 but the LED array 1 remains off while the rest correctly continue to flash sequentially one by one.
I know that with other 4017/555 circuits the 1N4148 work with or without driver transistors, (Fig2). I don’t know too much about mosfets so I am guessing at what the problem may be. The diode voltage drop, wrong type of diode, wrong resistor values, too much or too little or no voltage at Q1 gate? Or is it something else? The 4017 is moving so fast its hard to get a steady voltage reading with a dvm.
Any help here would be much appreciated
Thanks guys
I have assembled the following circuit (Fig 1), originally obtained from:- https://www.twovolt.com/2016/11/30/10-channel-chaser-mosfets-output-driver-using-lm555-cd4017/
The only difference being R4 to R13 which are 470R because I did not have any 100R resistors at the time of assembly.
It is however working well and flashes sequentially from Q0 through to Q9.
I would like to change the flash pattern by using some 1N4148 diodes as in so many other similar circuits that may be found on the net. (ie. Fig 2)
I always make very small changes/additions/modifications to existing circuits because it is easier for me to see if I am going in the right direction so I started off by dropping in the first 1N4148, (D1, Fig 3).
And now here is the problem that I am struggling with. The LED array 1 attached to Q1, D1, R4 remains light while the rest correctly continue to flash sequentially one by one.
When I disconnect the gate of Q1 from the D1 cathode and connect it to D1 anode (effectively removing D1), everything works correctly.
I have tried swopping the direction of D1 but the LED array 1 remains off while the rest correctly continue to flash sequentially one by one.
I know that with other 4017/555 circuits the 1N4148 work with or without driver transistors, (Fig2). I don’t know too much about mosfets so I am guessing at what the problem may be. The diode voltage drop, wrong type of diode, wrong resistor values, too much or too little or no voltage at Q1 gate? Or is it something else? The 4017 is moving so fast its hard to get a steady voltage reading with a dvm.
Any help here would be much appreciated
Thanks guys
Attachments
-
423.6 KB Views: 32
-
104.2 KB Views: 32
-
170.3 KB Views: 30