Im trying to duplicate this circuit board (pictured). Can anyone help me build one? Ill pay upfront

[...King-Loui$-Xlll...]

 

[Ramussons]

Agreed C1 is non polarised, but symbolically, it's wired reverse.

 

[Pommie]

The schematic and the pcb don't even come close to matching.

Mike.

 

[JonSea]

There are at least 6 resistors, a transistor and a transistor or voltage regulator with a heat sink missing. The schematic is tough to follow too.

 

[AnalogKid]

What is with the 555 footprint?

What is the device supposed to do?

What are the labels on the panel components?

Where are you located?

ak

 

[Les Jones]

And yet another problem is the 555 would not work with a value of 10 ohms for R1. The discharge transistor would not be able to pull pin 7 low and would probably destroy itself trying.

Les.

 

[audioguru]

The schematic drawing software makes many wires crossing over other wires. What a mess.
With only 10 ohms for R1 then pin 7 will be low most of the time and the 555 will get very hot and R1 will also get very hot.
I fixed it:

 

[jpanhalt]

I redrew the schematic a little differently and avoided a lot of the crossings:

**broken link removed**



I also note that the resistors values are unusual. According to AN170 that applies to the NE555,

To provide best operation, the current contributed by the RA path should be minimized so that the majority of discharge current can be used to
reset the capacitor voltage. Hence it is recommended that a 5k value be the minimum feasible value for RA (edit: R1 in the schematic). This does not mean lower values cannot be used successfully in certain applications, yet there are extreme cases that should be avoided if at all possible.

The calculated frequency is about 69.7 kHz with a duty cycle close to 50%. What is the circuit used for?

John

EDIT: Re D1 across R2
This is from AN170:

It is used to get duty cycles lower than or close to 50%.

EDIT#2: Like an idiot, I just plugged the values into a calculator. That was an error. Charging C2 via the diode will be very quick, so the frequency will be controlled by R2 and will be higher. Duty cycle will not be 50%.

 

[ChrisP58]

If you really need 50% duty cycle, a far better way is to run the 555 at twice the frequency and run it's output through a D type flip-flop to divide that by 2.

 

[jpanhalt]

Agreed, but given the choice of component values, I don't think 50% duty cycle is the goal.

I am waiting for that "up front money" to materialize. Maybe some prince in Nigeria knows where it is.