12v=19v 4,7A dcdc

[N-Channel]

I just looked at the sheets again. For the FT-140-77, at 50kHz, you are good for ~300W. For the FT-240-77, at 50kHz, you should be good for ~1.5kW before core saturation occurs.

[jamesrnz]

steve,

i have kinda gotten stuck on the mc33025, i like its method of current limiting versatility.

i have some etd59 double e's and some copper strip about 2 inches wide and 0.025" thick.

i was trying to do too big of step changes in input to output voltages so the toroids gave me trouble.

PLUS!!! my layout really sucked in huge amounts.

I have found that many of my control wiring methods were no good.

i have taken to twisting control grounds and signal together and taking care with ground loops. to get rid of mechanical buzzing due to instabilities.............


my mosfets are stp60nf10, 80 amps 100 volts 300 w 320 amp pulse

my rectifiers are stps80150cw, 2x40amp 150 volt to247 common cathode, one in each leg

i tested it with just 55 amps flowing though it of 13v no boost to see how the temp was, sort of for a baseline...

the strips i used for the high current got to about 130f they are 0.25x.0.025.

the transformer windings got to about 120f the transformer is etd50E-E with 160x#36 "litz" wire.
jim

the rectifiers got to about 130f each drawing roughly 27.5 amps

the inductor is a toroid of about 30x#24 77 material maybe an ft140 or 190 it gets about 115f

i'm not sure where the rectifiers are getting hot at, maybe the common cathode lead is to small for contiuois current, i may parallel another set or go wth a d0-5 stud mount like sd51.

i am running it at about 135khz, the cores seem to calulate out very conservitavly at that power level.

i am running 13 Vin to get 17.5 Vout at 6 amps boost right now to stabilze the control wiring and feed back before moving up.

a fellow ham was watching me last year when a loss of control happened things blew up rather dramatically, when he exclaimed," you just don't let the smoke out, YOU LET THE FIRE OUT TOOO!!!!"

[N-Channel]

Hope the fireworks show was worth it. BTW, we will be operating QRP this year, 16A. Our club call is K8UO. I will be on the 40 DIGI station.

Toroids are not meant for wide input-output voltage ratios, as covering the entire core with low number of windings (say, less than 4T) can get tricky, and result in less-than-ideal coupling.

Just a little curious, Why such large currents for a 17.5V 6A output? At low input of 10V, your input current would still be only just under 17A Peak.

[jamesrnz]

i'm not sure what you are refering to about large currents?

[N-Channel]

Well, 17.5V @ 6A is only 105W. At worst case (taking into inefficiencies) this is still only 17A. Not sure how this translates to 27.5A. Maybe I am missing something.

Anywho, 135kHz (67.5kHz switching) is pretty good. For the FT-240-77, you will be good for a solid 1.5kW.

Other note- Finished Gen-set. 6HP B&S Mower engine driving Delco 140A Alt charging 170Ah batteries, running Xantrex Prosine 1800. Everything works except for...........................the Alternator! Making electricity was kinda the whole idea in the first place. Head Scratchin' here.

[jamesrnz]

ahhhhhhh........

ok the 27.5 amps came from the static (non-boost) current flow at 55 amps to a load at 13v just to see how the temps would get to, sort of whwrere theweaknessess are so now any additional heat would be from "dynamic" operation.......

it is putting in about 9 amps at 13 to get 17.5 at 6 amps...... still trying to get the pesky noise out of the transfomer......


what kind of alternator do you have? is the feild powered directly by th battery? and do you have 10 ohm to the regulator output? ( if it is a delcotron)

[N-Channel]

It IS a Delcotron. CS-144, 140A model with the PLI(F)S plug. The thin black field wire goes to the battery, via a 10-50W in-line resistor paralleled with the idiot light. The thick, red sense wire goes to the main B+ Binding post, essentially a 3/8" 2.5 inch bolt. I momentarily touched it to B+ and the V(out) jumped from ~12.8V to 14.7V. That was two weeks ago. Now when I touch it, I get just the battery voltage of 12.8V-12.9V. I'm wondering if by momentarily bypassing the resistor-light combo, did I fry the regulator? I need to resolve this issue ASAP, as it is being used for a public event saturday night. UGH!

I hope those reading this thread don't think we're getting off-topic. Siince this deals with +12V systems, it addresses the thread's title: 12v=19v 4,7A.

[jamesrnz]

do you have the idiot light resistor in the circuit and does it goto switched b+?

[jamesrnz]

this is a good resource

http://www.extreme4wheelin.com/tech/...ators/tech.htm

[N-Channel]

Cool. Thanks! I said "screw it" and went to a local alt/gen/starter rebuilding shop, told them my situation, and they fixed me up. New "411" (standard) regulator: $15.00. Apparently there are fifteen (15) different regulators for the CS-144 series. depending on the use. The '411 is for general charging, electrity generation, & general use. I will repalce it tonight & report back tomorrow. Now back to our regularly scheduled programming............ Also, I will look at that link tonight. THX again!