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Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
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"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
Oh joy -- so, do you have the frequency headroom to use a lower inductance coil with the same core, to get the saturation current up?
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My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
Has the value of inductor been selected properly? The rule of thumb for a boost converter in continuous conduction mode is L = (V * D)/(R*I_l*f), where the parameters are evaluated at the _lowest_ specified (worst case for a boost) input voltage. V is the input voltage, I_l is the DC inductor current (I_o/(1-D)), D is the duty cycle, f is the switching frequency. R is the "ripple current ratio" and has an optimum value of 0.4 for continuous conduction mode in most cases.
At low voltages the inductor can be sized solely based on the DC load current requirements - if the current limiting is fast enough it doesn't matter if the inductor saturates under abnormal conditions.
If the inductor is still too big maybe use discontinuous mode instead? It'll be harder to stabilize, unfortunately.
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| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
That's where my thoughts are progressing... ...Jim Thompson
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| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
But 4 ohms d.c.r. means it'll drop 600mV @ 150mA. Increasing f by a factor of 3 reduces i^2*r loss by that same factor. Or, keep the loss and trade for a smaller L and C.
Switching inductors without magnetic shields make RFI, magnetic nasties, etc. Shielded are better.
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Your "questions" are little more than trolls designed to attract and
focus attention on you and, since you asked for "help" and it was
offered and you rejected it, out of hand, you're an ingrate with an
agenda disparate from ours, which is to help.
Ian _and_ a notable other poster on this topic are severely ignorant about the real world.
PWM BUCK is trivial. I chose BURST for the hub dynamo because it would be a freebie around the 555, and I was intent on rubbing the 555 up some snobbish noses ;-)
PWM BOOST is NOT trivial, though I'm well on my way to an off-the-wall STABLE solution... found by running the math instead of my mouth. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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