powering a 555 off mains

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View




 I'd like to make a 555 PWM speed controller to drive
a mosfet and switch a 240V DC motor that normally runs off
a TRIAC circuit fed into a bridge rectifier. The TRIAC
controller normally is set up to output 240V max from the
340V rectified mains and while it works ok has no low down
torque and outputs an awful lot of RF interference.

 My main query is this: what's a simple effective way to
generate the 12V DC or so to power a 555 IC off 340V DC?.
I was mainly considering a power resistor/zener combination.




Re: powering a 555 off mains


put finger to keyboard and composed:

Quoted text here. Click to load it

That's how it's done in cheap household appliances, eg timers,
toasters.

See http://www.users.on.net/~fzabkar/Toaster_5698123.pdf

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: powering a 555 off mains



Quoted text here. Click to load it

Hey Franc
Did ya get that lighting cct sorted ??

--
Cheers .......... Rheilly P



Re: powering a 555 off mains


On Wed, 30 May 2007 17:54:13 +0800, "Rheilly Phoull"

Quoted text here. Click to load it

If you're referring to that recent continuation of a very old thread
(22 Feb 2007), then the OP with the problem was Nick Hobbs, not me.

http://groups.google.com/group/aus.electronics/msg/0f2f422b77dac3a7?dmode=source&hl=en

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: powering a 555 off mains



"Mark Harriss"

Quoted text here. Click to load it


**  Totally nuts idea.

Quoted text here. Click to load it


**  ROTFL

So what fool's magic will make using a MOSFET any different ??

Go have a look at a  *half wave*  SCR drill speed control -  low speed
torque is kept high by the use of back emf induced feedback of the firing
phase.

Many kits designs have been published by EA and SC.



......   Phil



Re: powering a 555 off mains




I wondered if my post would bring you flapping out
of the woodwork of Nostradamus' coffin.

Re: powering a 555 off mains


put finger to keyboard and composed:

Quoted text here. Click to load it

Is this a treadmill application? Just curious ...

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: powering a 555 off mains


snipped-for-privacy@iinternode.on.net says...
Quoted text here. Click to load it


 Production gemstone faceting machines Frank, the speed controller
sits in an earthed, cast metal box and they've been made for 40
odd years using triacs but the lack of low end speed and the bad
interference as well as some false triggering problems when you
have more than one unit on the same powerpoint makes me want to
evaluate a slightly more recent design principle.

Re: powering a 555 off mains


put finger to keyboard and composed:

Quoted text here. Click to load it

FWIW, I see used MOSFET based (?) PWM treadmill DC motor controllers
(120V) on Ebay for US$60.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Site Timeline