Proximity sensor - help for a school project

[DWBH]

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(Park-Aid - RED - Page40)
(Park-Aid Modification - RED - Page138)

R1_____________10K 1/4W Resistor
R2,R5,R6,R9_____1K 1/4W Resistors
R3_____________33R 1/4W Resistor
R4,R11__________1M 1/4W Resistors
R7______________4K7 1/4W Resistor
R8______________1K5 1/4W Resistor
R10_____________1K 1/4W Resistors
R15_____________3K3 1/4W Resistor
R16___________330K 1/4W Resistor
R17___________470K 1/4W Resistor
R18___________150K 1/4W Resistor


C1,C4___________1µF 63V Electrolytic or Polyester Capacitors
C2_____________47pF 63V Ceramic Capacitor
C3,C5_________100µF 25V Electrolytic Capacitors
C6______________1µF 63V Electrolytic or Polyester Capacitor


D1_____________Infra-red LED
D2_____________Infra-red Photo Diode (see Notes)
D3,D4__________1N4148 75V 150mA Diodes
D5-7___________LEDs (Any color and size)
D8,D9,D10______1N4148 75V 150mA Diodes


IC1,IC4_________555 Timer IC
IC2___________LM324 Low Power Quad Op-amp
IC3____________7812 12V 1A Positive voltage regulator IC

BZ1___________Piezo sounder (incorporating 3KHz oscillator)


IC1 forms an oscillator driving the infra-red LED by means of 0.8mSec. pulses at 120Hz frequency and about 300mA peak current. D1 & D2 are placed facing the car on the same line, a couple of centimeters apart, on a short breadboard strip fastened to the wall. D2 picks-up the infra-red beam generated by D1 and reflected by the surface placed in front of it. The signal is amplified by IC2A and peak detected by D4 & C4. Diode D3, with R5 & R6, compensates for the forward diode drop of D4. A DC voltage proportional to the distance of the reflecting object and D1 & D2 feeds the inverting inputs of three voltage comparators. These comparators switch on and off the LEDs, referring to voltages at their non-inverting inputs set by the voltage divider resistor chain R7-R10.

The original Park-aid circuit was retained, but please note that the input pins of IC2B, IC2C and IC2D are reversed. LEDs D5, D6 and D7, as also resistors R12, R13 and R14 are omitted. IC2B, IC2C and IC2D outputs drive resistors R15, R16 and R17 through D8, D9 and D10 respectively, in order to change the time constant of a low frequency oscillator based on the 555 timer IC4.
This allows the Piezo sounder to start beeping at about 2 times per second when bumper-wall distance is about 20 cm., then to increase the beeps to about 3 per second when bumper-wall distance is about 10 cm. and finally to increase further the beeps frequency to more than 4 beeps per second when the distance is about 6 cm. or less.


I've come up with this pcb layout, but I'm not sure if it's 100% accurate. Can you please give me a hand and verify it?

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There's another resistor soldered directly on pins 2 and 13 of the LM324, but it doesn't show on the layout.

 

[Mikebits]

So what exactly is your question? Do you want someone to check your layout for you? Not gonna be me. Print out your schematic, and your layout, take a yellow highlighter pen and start checking each trace on the layout and compare to your schematic. Highlight each trace you verify to match your schema. That is how it is checked.

 

[ericgibbs]

hi,
Its a nicely presented project.

My only complaint would be in checking the pcb layout,, the circuit diagrams dont have component values only a parts listing.
This means its necessary to keep jumping back and forth from the cct, parts list and layout which is time consuming.

As Mike says, take some prints of the cct and layouts and use marker pens to trace out the layout bit bit.

Another way is to use Windows Paint shop and go over the tracks with different colours.

Does this help.?

 

[Mikebits]

Remember those old light tables Eric... I have verified many layouts that way. Ahhh the good ol days. Oh and you have not lived until you have layed out a ckt board with rolls of thin black tape

 

[ericgibbs]

Remember those old light tables Eric... I have verified many layouts that way. Ahhh the good ol days. Oh and you have not lived until you have taped out a board with rolls of thin black tape

Either at *2 or *4 size,,,double sided....

 

[Mikebits]

Either at *2 or *4 size,,,double sided....

I once did a multilayer board using tape. It was a real..real... um insert colorful adjective here.

 

[ericgibbs]

hi DWBH,

There is a difference twixt the cct and layout, see this image.

Part done with Paint Shop

 

[colin55]

This "Proximity Sensor" is an ideal circuit for conversion to a microcontroller - just 11 parts.

I converted a "Phone Number Memory" project from 16 chips to a single microcontroller and increased the capability from a set of diode matrix cards to 30 number memory.

 

[DWBH]

hi DWBH,

There is a difference twixt the cct and layout, see this image.

Part done with Paint Shop

That section (signal amplification) is done with pins 8, 9 and 10. I thought it'd make the layout more tidy.
So, for the IR signal amplification I used opamp C (8,9,10) (instead of opamp A). For the voltage comparators I used opamp B, A and D, instead of the opamps B, C and D respectively.

I should have updated the schematic, and put the parts numbers on the layout. Sorry.

 

[ericgibbs]

That section (signal amplification) is done with pins 8, 9 and 10. I thought it'd make the layout more tidy.
So, for the IR signal amplification I used opamp C (8,9,10) (instead of opamp A). For the voltage comparators I used opamp B, A and D, instead of the opamps B, C and D respectively.

I should have updated the schematic, and put the parts numbers on the layout. Sorry.

hi,
Do you want it rechecking, if Yes, then post the updated circuit. [Just the cct diagram]

When checking layouts, I use Paint Shop, it makes the job very easy.

 

[DWBH]

Here are the updated schematic and diagram.
Don't mind about part values.
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Also, important to say that R9 is NOT on the parts diagram, as it is going to be soldered directly on pins 2 and 13.

 

[DWBH]

I updated the images on my last post.

 

[Arkham00]

Which CAD software was used for the schematic and the PCB of this project?

 

[ericgibbs]

I updated the images on my last post.

hi,
Give me a while, Ill check it thru.

 

[DWBH]

Which CAD software was used for the schematic and the PCB of this project?

PCB Wizard (version 3.5 Pro, I think).

 

[ericgibbs]

hi DWB.

Not quite there yet.!

 

[DWBH]

I think it's all set now:
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[ericgibbs]

I think it's all set now:

Ok, Ill give a check thru, will post later today.

You understand why I am not making any corrections for you to the layout.

 

[ericgibbs]

hi,
Just 2 errors, marked on the layout.

Your'e making me earn my money..


EDIT:
Just a test for ElectoMaster

 

[DWBH]

Yes, R9 is not represented, as it is going to be soldered directly on pins 2/13.
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