Replace LED in a circuit to drive 12 volt bulbs

[Roxy2]

Hi, I am new to this forum so bear with me. I am buying a couple of 'dice' kits which run LEDs. This circuit seems to fit the bill! What I want to know is if I replace each LED with a MOC3021 optocoupler triac driver, or similar, will the circuit still work (as there are 2 led's in series) and can the output switched side of the MOC3021 then be used to switch an ac circuit of 12 volt. by direct connection. And the switching will occur in the same manner the original LEDs in the circuit would?

 

[ronsimpson]

The MOC3021 needs 15mA to turn on.
Are the LEDs red?
I would change the resistors on the LEDs from 1k, 330, 330, 330 to 330, 330, 330, 330 and replace the LEDs with the MOC3021.

 

[Roxy2]

the leds are red 3mm. And the MOC3021 will provide direct switching for a 12v ac supply? Why would you change the 1k resistor?

 

[bailey45]

You need to change the resistor to ensure enough drive current for the opto coupler

 

[colin55]

I see you are using my circuit. But I have not received your order for the kits.
If you use low-current 12v globes, and B338 / BC328 transistors, you can connect them directly and put two in parallel and use a 12v supply.

 

[ronsimpson]

You need to change the resistor to ensure enough drive current for the opto coupler

9volt supply - 1.5 volts for opto (LED in opto) - 0.5 volts for transistor = 7 volts across resistor (1k=7mA)

 

[Roxy2]

Sorry, I should have said the circuit allows me to run it from 6 - 15volt. I would be running it at 12v. Im still slightly confused over the resistor issue as the tracks with 2 LEDs have the 330 resistors but are remaining unchanged.

 

[Roxy2]

I see you are using my circuit. But I have not received your order for the kits.
If you use low-current 12v globes, and B338 / BC328 transistors, you can connect them directly and put two in parallel and use a 12v supply.

Actually Im using velleman kits but didn't have a drawing for it, but i believe they are the same. I came across your circuit in google images but couldn't find any contact details for the person who drew it. Obviously its you. Im actually looking at driving 12 volt dc LED bulbs now (the sort with 6 smd's on board). Something like these, **broken link removed**
Is the transistor you say instead of the 547 and 557?

 

[colin55]

Does the Vell kit have transistor drivers?

Use the BC338's and put the LEDs in parallel

 

[Roxy2]

Does the Vell kit have transistor drivers?

Use the BC338's and put the LEDs in parallel

This is what Ive found for the Velleman. https://www.electro-tech-online.com/custompdfs/2012/07/mk109.pdf

Thanks for the help by the way.

I was basing my original idea on finding this. See attached image.

 

[Roxy2]

How much are your kits posted to the UK? Could you supply the components needed to run 12v LED 'arrays'?
I would want 2.

 

[colin55]

The Vell cct is nothing like mine. It only has a 10mA drive-current. My circuit has slow-down.

 

[Roxy2]

Ok, I didn't mean the same, I meant similar. If you mean by slow down as in the dice roll and slow to a stop, the vell one does too.

 

[Roxy2]

Velleman DIce to power 12 volt LEDs

I have just build a Velleman dice circuit (see attached). I would like to use this circuit to run some very large dice for a charity event. So therefore need big lamps. I have decided to use these - **broken link removed**
As an experiment I have removed 1 led from the circuit board and fitted a 4N25 Optocoupler as I had one lying around. I then attached a 12volt supply through the emitter/collector and then onto a similar LED bulb as above. The flashing of this 12volt LED is fine and it doesn't seem to effect the circuit, however when it is supposed to be off for example when the dice rolls 1 it still has a very small glow.

Is this optocoupler wholly suitable or should I opt for a MOC3021 or similar? Is there anything else that perhaps needs changing such as the resistor ratings?

Hope this all makes sense.

 

[colin55]

when it is supposed to be off for example when the dice rolls 1 it still has a very small glow.

What is the value of the series resistor? Put a resistor across the LED of the optocoupler.

 

[Roxy2]

What is the value of the series resistor? Put a resistor across the LED of the optocoupler.

All the values are on the attachment for the velleman drawing (post 14).

Im currently using the place of LED 5 as I experiment.

 

[colin55]

Remove the input of the opto coupler. Does the LED still glow?

 

[Roxy2]

Ive tried this circuit, without the 47R resistor and it seems to be ok. I have ordered up the components to make up a full set now and will report back once done.

 

[ericgibbs]

hi Roxy,
Will you please post the circuit diagram here, the link requires that we have to sign in.

E

 

[Roxy2]

hi Roxy,
Will you please post the circuit diagram here, the link requires that we have to sign in.

E

Done - sorry I was in a rush!