02-08-2012, 06:22 PM
(This post was last modified: 02-08-2012, 06:24 PM by Robert Darwent.)
Hi John,
OK I see what you intended, in that case you are spot-on with 10.68 uF for the capacitor value.
That's fine John, I understand you not wanting to look too far ahead. However something to consider, if you look at the same spreadsheet results for the 'dropper resistor with diode' it gives just 50 ohms at 4.5W to achieve the same as using the 10.68 uF capacitor with 33 ohm surge limiter.
It might be worth experimenting with this as an alternative. It's a far less amount of heat to dissipate than your earlier 2 x 270 ohm in parallel arrangement, would take up less room and so be easier to fit inside the screening can, as well as being considerably cheaper in terms of component cost. A 1N4004/1N4005 type would be suitably rated for the diode.
Regards
(01-08-2012, 08:39 PM)Geaney Wrote: The slight difference in cap values is because I selected an input voltage of 120V versus 110V (apologies for the typo). In any case I've ordered up both 10uF and 12uF motor run caps just in case.
OK I see what you intended, in that case you are spot-on with 10.68 uF for the capacitor value.
(01-08-2012, 08:39 PM)Geaney Wrote: In general I'd say my plan to run the set off 110v is down to lack of experience/confidence with this type of set. As I get more comfortable with these types of design I'm sure I will be more adventurous and jump more than one stage at a time.
That's fine John, I understand you not wanting to look too far ahead. However something to consider, if you look at the same spreadsheet results for the 'dropper resistor with diode' it gives just 50 ohms at 4.5W to achieve the same as using the 10.68 uF capacitor with 33 ohm surge limiter.
It might be worth experimenting with this as an alternative. It's a far less amount of heat to dissipate than your earlier 2 x 270 ohm in parallel arrangement, would take up less room and so be easier to fit inside the screening can, as well as being considerably cheaper in terms of component cost. A 1N4004/1N4005 type would be suitably rated for the diode.
Regards
