Schematic

Karen

I watched the video with the rotating fan and was intrigued the way you made the connections under the board and for the first time began to get an idea. However the  connection part was sped up so still a little confusing. The schematic you have colour coded is a great help and almost what I need. However I do understand from your drawing the run of the positive and ground runs but what is, and always has been is all the other lines within the schematic that you have not coloured. Which is positive and which goes to ground. I know you will think this is a ridiculous question but I don’t follow the positive and ground runs inside the schematic.

Im not conversant with the 555 timer so don’t know what each pin does.

From the base of M1 the - sign is connected to the diode D3 which in turn connects to the positive plane, It appears to me, the novice, that negative is connecting directly to positive the diode D3.

From R1 to VR1 and to R2 appear to come from the positive plane and stops at D1, but then from VR1 it looks like power goes through D2 and also picked up below D1. I am so confused which is positive and negative. I know you will be thinking I am overthinking it but if you could draw on the flow direction and colour the lines within the schematic to show which is which. Is it that I’m not understanding the way the components operate that is confusing me?  I think i need to be next to someone while the circuit is built from a schematic to help me understand how it is put together.

love your videos.

thanks

Roger

Karen

I watched the video with the rotating fan and was intrigued the way you made the connections under the board and for the first time began to get an idea. However the  connection part was sped up so still a little confusing. The schematic you have colour coded is a great help and almost what I need. However I do understand from your drawing the run of the positive and ground runs but what is, and always has been is all the other lines within the schematic that you have not coloured. Which is positive and which goes to ground. I know you will think this is a ridiculous question but I don’t follow the positive and ground runs inside the schematic.

Im not conversant with the 555 timer so don’t know what each pin does.

From the base of M1 the - sign is connected to the diode D3 which in turn connects to the positive plane, It appears to me, the novice, that negative is connecting directly to positive the diode D3.

From R1 to VR1 and to R2 appear to come from the positive plane and stops at D1, but then from VR1 it looks like power goes through D2 and also picked up below D1. I am so confused which is positive and negative. I know you will be thinking I am overthinking it but if you could draw on the flow direction and colour the lines within the schematic to show which is which. Is it that I’m not understanding the way the components operate that is confusing me?  I think i need to be next to someone while the circuit is built from a schematic to help me understand how it is put together.

love your videos.

thanks

Roger

Hi Roger,

I really do understand your frustration, but schematics can represent circuits that are very dynamic. What might be positive at one instance may become negative in another.  Then, there are relative degrees of positive (represented by number of volts above ground).  A voltage divider may take a 5 volt supply and generate a mid-point that is less than 5 volts, but still more positive than ground (0 Volts).

In your comment above, you zeroed in on one of the more obscure aspects of the circuit, diode D3.  99% of the time the diode does absolutely nothing, it exists to route current back into the power rail when the motor is switch off (de-energizing Q1).  The motor has a magnetic field around it when the motor is driven (Q1 on), when switched off, the magnetic field collapses and generates a large voltage spike that could damage components in the circuit.  Diode D3, routes this current into the power rail.  Why not to ground?  If the diode directed current to ground, it would also short current to ground when the motor was on (not a good thing).  This concept is a little more advanced that beginner electronics, but it is an important lesson.

When I was first learning electronics, I was fascinated by schematics.  I could not understand them in their entirety, but with time and education they became clearer and clearer.  Be patient, time and studying will allow you to understand schematics more fully.

Gene