Any electronics experts here?

[HB13DISH]

A linear multi-turn potentiometer might be a good replacement for the single turn pot that you are using now.
If these parts no longer exist, let me know and I will look in my drawers for one that I used many years ago for a prototype project and I will be happy to send it to you by post.
I think it was 50 Kohm, linear, with 10 turns but with short shaft length so you might need a shaft extender.
The trouble with such a part is that you need a counter knob or just count from the begining for the number of turns (precise angle) that you need).

 

[mhku]

Thanks for the offer but I think it'll cost more in postage than it's worth

I'm considering one of these sub-miniature ones (30p):

_http://www.maplin.co.uk/Search.aspx?criteria=N43BR&DOY=8m6

The only drawback is finding a suitable knob as I think it's meant for attaching to a PCB rather than to a permanent knob.

 

[HB13DISH]

If the multiturn pot can help you, then just let me know and I will post it.
I think it is a Bourns 3540 model. Check the body size and if it can fit in the package.
The sub-miniature type is meant for a preset level and forget it apllications. not for different settings all the time.

 

[mhku]

I have another dumb-ass question...

I'd like to build the High Voltage adapter circuit in the attached diagram. Maplins sell the optocoupler but it's been 20 years since I did physics at school- what rating does the Omega symbol mean?

(_http://www.chemie.unibas.ch/~holder/nikonflash/coolflash.html)

 

[Robbo]

Ohms.

A measure of resistance.

 

[mhku]

doh! One resistor is labelled 1M and the other 1MQ (replace Q with Omega)- they're both 1M ohm?

Looks like Maplin don't sell 8.3 ohm resisitors or did I read the circuit wrong?

 

[Topper]

Ohms as stated in the case of that diagram 8.3 ohms and 1 Megaohm


edit too many cooks... I'm off to bed

 

[Robbo]

Yes , the omega symbol is not strictly necessary as the graphic shows it is a resistor, so 1M is the same as 1MQ (Q=omega)

You will also see 1k


Also used is for example 2k7, which is 2.7 k ohms


and 2R7 2.7 ohms


8.3 ohms might be written as 8R3



They have 8.2 ohms in the 3W variety.

_http://www.maplin.co.uk/searchtemplate.asp?criteria=4.7%20OHM%20RESISTOR

 

[mhku]

Cheers! I could have googled it but..

 

[mhku]

Maplin sell a 0.6W 8.2R resisitor and all the other bits but stuck on the board. Attached is a photo of the finished item (slightly different components).

Is the board matrix board and what's the difference between strip, dot matrix, plain etc? Are there any alternatives?

_http://www.maplin.co.uk/module.aspx?ModuleNo=47480&doy=27m6
_http://www.maplin.co.uk/module.aspx?ModuleNo=1917&doy=27m6

Thanks

edit: I'm guessing stripboard (_http://www.kpsec.freeuk.com/stripbd.htm)

 

[Llew]

A pice of stripboard will do fine. Arrange the components on the board first to get an idea of the size you need before cutting it.

You could draw out the circuit 'wiring' (a sheet of graph paper is ideal) before cutting the tracks, although it shouldn't be necessary with such a simple circuit.

If you want to splash out, Maplins do a stripboard cutter, but a drill bit can do the job OK.

It might be a good idea to get a DIL holder for the opto (Maplins CJ79L) in case of any wiring mistakes, so you can easily remove the opto.

Llew

 

[mhku]

Cheers Llew. Maplins have got free postage until Sunday so I ordered the bits (even though I live near one) but got the stripboard from fleabay as it was cheaper.

Next week the fun and burning will begin (again)

 

[mhku]

Still not got it sorted.

Is the orientation of the optocoupler the same as the one in the cut-out (with the red outline)?

Also, what does the right-pointing arrow signify? Is it that pins 1 and 2 are soldered together?

 

[Robbo]

You need the datasheet for the device to obtain the pinout. I would imagine that the arrow represents the opto-coupling.

 

[Llew]

No, check the schematic box in page1 of this PDF. Pins 1 (top left of your circuit) & 2 (bottom left) are the IR diode, and 6 (top right of your circuit) & 4 (bottom right) the triac switch.

The arrow merely shows the direction of emission of the light within the opto chip.

 

[mhku]

It's this part (althouh I did buy one 3020):

_http://www.maplin.co.uk/module.aspx?ModuleNo=2223&doy=13m7

Cheers for the pdf - I'll read it now.

 

[Llew]

I'm not sure if that opto is suitable for that circuit (transistor opto output). I think you need the triac output for your flash dongle

 

[mhku]

Does this match the circuit in post #33?

If I use a 3020 are these the correct pins:

A= pin 1
B= pin 6
C= pin 2
D= pin 4

(blue is -ve)

 

[Llew]

Yes, the layout is correct - I'm trying to figure out how the input diode is turned on, as I'm not familiar with the action of the triggering input, particularly the use of the 3V cell ( biasing?)

 

[mhku]

The idea of the circuit is that the left hand side is connected to a radio transmitter (or camera) and sends a signal through the circuit to the flash (the right hand side of the circuit). The circuit is to stop 300v being sent back to the transmitter (or camera) when the flash fires (the trigger voltage).

There are lots of diagrams on the web but no photos of the circuits for ee-jits like me

A Lithium cell provides power for the camera side circuitry.