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Hi kv,
the bridge rectifier is drawn the wrong way.
Please compare.
Boncuk
Correction,
the diode is useless as drawn.
Connect it that way.
Boncuk
Hi Kv,
it doesn't really matter if the switch I used in my schematic is a switch or a relay. The function remains the same. (Switch or relay closed = OFF)
Please be aware of the odd values of resistors and capacitors you used in your design. You will most likely not be able to get parts like these.
Instead of 4K I used 3K9 (standard E12 value) and instead of 110nF I used 100nF.
A DC smoothing electrolytic cap of 100µF instead of 10µF won't be a mistake.
Regards
Boncuk
I was thinking I could pick one out myself but I should have known it would be more complicated.
I have a 5vdc 400ma supply from a status Pin on a parrellel port. I have a voltage I intend to pull to ground using Isolated relay contacts.
The relay's I have been looking at are bigger than the supply voltage I want to use.
Any suggestions.
kv
hi kv, ref your PM.
If I read the first post correctly , I think what you are saying is:
You want to switch a relay ON, using the 5V [ 400mA rated] supply from a device port pin.
The contacts on the relay you switch ON, will then switch ON another device that has a higher voltage and current.
Am I close.?
Um ya. I think ?
kv
I've not read the whole thread and to be honest I don't want to.
I've just read the first post and briefly skimmed through it.
The circuit you're posted doesn't appear to work.
The 120VAC part looks like a transformerless power supply which will blow up as there's nothing to limit the current.
What's the isolation transformer with +5V and +12V doing at it's secondary?
I don't know why on earth you're using a 110nF capacitor and 4k diode when standard values such as 3k9 and 100nF are near enough.
Sorry but this doesn't make much sense to me. I'm sure this has probably been discussed before but why not just use a relay?
You have to be sure before I can suggest a solution.
What are you wanting to switch ON with the relay contact.?
The bottom circuit. But, I think hero is saying it will just fry anyways the way it's hooked up. So I guess I should build another board the way bancuk is showing me.
But I still need to control it from my port pin 2 with a reliable circuit.
hi kv,
Like to help if I can.
Im not interested in previous suggestions, just answer my posted questions.
What are you wanting to switch ON, ie whats the end result you want.?
Ok, I need to turn on a light. My circuit on the bottom is the one I want to do that with by closing the base of Bc557.
Thank you for your response.
kv
Ok.
You want a relay like the type in this attachment, with the 5V coil.
You connect the relay coil across the +5V [400mA rated] and 0V.
Connect your light and mains supply in series with the normall open relay contact.
Do you follow OK.?
Ok. yes
I have no way to see the PDF I was working cleaning up old programs. I will download another viewer.