Can I start this astable 555 with low lock from TTP223 or use Bilateral Switch

[ThomsCircuit]

Id like to incorporate a touch switch into this circuit. i planned using the output from a TTP to a TC4S66F then the output from that to the GND of the 555. There may be a chance that i can skip the TC4 and use the low lock output from the TTP straight to the GND of the 555. if that is not the best solution then could you help me configure the TC4 to turn on the 555 via the output of the TTP like i originally planned?

TTP & TC4 5 volts
Rest of circuit 12 volts

 

[eTech]

Hi
This assumes the Q output of the TTP223 is normally high and goes low when pad is touched. Q1 will hold the 555 in reset mode until TTP223 "Q" goes low and turns off Q1, the 555 will then run. When Q goes high again, the 555 will stop oscillating.
Add only the parts and connections I've shown circled below.

 

[ThomsCircuit]

Add only the parts and connections I've shown circled below.

Thank you so much. Ive also replaced the batteries with a 12v 1a wall wart.
What i understand is the 10k to GND at the base of 3904 is to do with the gain of this particular resistor.

 

[eTech]

Thank you so much. Ive also replaced the batteries with a 12v 1a wall wart.
What i understand is the 10k to GND at the base of 3904 is to do with the gain of this particular resistor.

It ensures the base is not floating and the 3904 is fully off.

 

[ThomsCircuit]

Lots of work but I managed to place all the components. Being that the board floats in the space provided i was able to place components on both sides of the PCB.
I followed as many guidelines as possible. I do have two areas where 3 tracks intersect. I did my best to avoid it. All of my through hole GNDs have 4 spokes on their pours as well as many of the SMD components too. There as situations where the pads are too close to achieve 4 spokes but there are at least 3. I did alter the settings on the pour properties but not too much as i am unsure that if i close the gap too much it may cause more problems than its trying to prevent.

 

[eTech]

Lots of work but I managed to place all the components. Being that the board floats in the space provided i was able to place components on both sides of the PCB.
I followed as many guidelines as possible. I do have two areas where 3 tracks intersect. I did my best to avoid it. All of my through hole GNDs have 4 spokes on their pours as well as many of the SMD components too. There as situations where the pads are too close to achieve 4 spokes but there are at least 3. I did alter the settings on the pour properties but not too much as i am unsure that if i close the gap too much it may cause more problems than its trying to prevent.

Looks good.
But I would double check that the 3904 pin assignments are correct, just to be sure.

 

[ThomsCircuit]

You had me worried there. Many times the SMD pin assignments are different from the through hole version. I double checked and its correct. The collector is the center pin. It is connected to the reset pin on the 555. I did however find that i had the 5v+ and the touch pads were swapped. Until i have more experence in the components I wont have these boards made until i have the components in my possession. The last SMD transistors PCB pads were too small. Made it very difficult to solder.

 

[eTech]

Until i have more experence in the components I wont have these boards made until i have the components in my possession. The last SMD transistors PCB pads were too small. Made it very difficult to solder.

Yes...good idea. Many times PCB footprints are designed for automated assembly and soldering. The machines are able to hold tight tolerances. Not great for human assembly and soldering

 

[ThomsCircuit]

Many times PCB footprints are designed for automated assembly and soldering. The machines are able to hold tight tolerances. Not great for human assembly and soldering

The pads for the diode had almost no room to apply heat to the pad to affix the component. I wasn't happy with the placement and i damaged the board (slipped with the tweezers) trying to remove it. I was able to bridge the damaged track with a peice of soft copper but it meant not being able to re-apply the component. It worked out because the diode was acting as a flyback for the fan so it still worked without it.