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G8MNY > TECH 30.06.05 21:44l 74 Lines 3452 Bytes #999 (0) @ WW
BID : 52284_GB7CIP
Read: GUEST OE7FMI
Subj: Regulating 12v Generator Output
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<7M3TJZ<DK0WUE<I0TVL<CX2SA<GB7YFS<
GB7CIP
Sent: 050630/1813Z @:GB7CIP.#32.GBR.EU #:52284 [Caterham] $:52284_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (New Jul 05)
Small generators often provide unregulated charging outputs. These can easily
over charge your /P battery & cause damage & excessive battery voltages across
low power lamps & other kit.
Here is s simple efficient charge limiting SCR regulator that can be put unto
the lead at the battery end.
FEATURES
1/ Charge output gradually shut of at 14V (dependent on Zener voltage).
2/ Low loss (1v) as it is not a linear regulator.
3/ Generator connected LED, this lights when DC appears from the generator.
4/ Charged LED, gradually lights up as the battery needs less genny O/P for 14v
5/ Battery lead isolation, no battery DC on the generator lead.
6/ No battery drain, the circuit does not take current from the battery.
CHARGED LED
ÚÄÄ´>ÃÄÄÂÄÄÄÄÄ´>ÃÄÄÄÄ¿
³ +100u ³ ³
ÃÄÄ´ÃÄÄÄ´ 470
TRIP + ÃÄÄ2K2ÄÄÙ SCR ³ Fuse
ÚÄ´>ÃÄÄÄÄÄÄÄÄÄÄÂÄo--oÄÄÄÄ<<ÄÄÄÄÄÄÄÁÄÄÂÄÄÄÄÄÄÄÂÄÄÄÄ´>ÃÄÄÁÄÄÄ>>ÂÄo-oÄ>loads
³ ³ GENNY LEAD _³_ GEN 270 ³ CROCK³
³ ÚÄÄÄÄÄÄÄÄ)ÄÄÄÄÄÄÄÄÄÄ<<ÄÄÄÄ¿ \_/ OK ÃÄ´>ÃÄÙ ³
³ 20v ³ 20v ³ CON - ³ ³ LED _³_ ÄÄÁÄÄ 12V
ÀCCCCCCCCCÄ´>ÃÄÙ ³ ³ /_\'14.5V === BATTERY
========= ³ 1K ³ CLIPS³
ALTERNATOR ÀÄÄÄÄÁÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄ>>ÁÄÄÄÄ>
SCR mounted on heatsink
HOW IT WORKS
The raw DC peaking well over 20 volts off load lights the GEN OK led to the 1K
to -ve. The 20V also provides 14.5V on the zener. This puts 14V onto the gate
of the SCR via a blocking diode. If the battery voltage is much less than this
the SCR will be triggered & put nearly all of the 1/2 cycle of DC from the
generator into the battery.
As the battery charges the voltage rises & the SCR is triggered less & less, in
fact a crude form of phase firing naturally occurs, as the battery voltage
falls from the last current burst & the zener voltage rises..
_ _ ___.---...___.--- BATTERY VOLTAGE
/' `\ /' `\
| | | | .-""""-. .-"""-. ZENER VOLTAGE
³ ³ ³ | | | | |
V V V V V V
OFF LOAD GENNY DC ³ ³
PHASE TRIGGERS
| |
11V 14V
This does what you need for charging, turn the current down as the voltage
comes up.
If the charge current is small (small genny eg 8A max), the battery a big one
with low internal resistance, then the hum across the battery MIGHT be small
enough not to cause hum problems with kit. eg a 25Amp SSB rig.
DC WITH OTHER LOADS
Some generators warn you not to use both DC & AC outputs at the same time. This
may not be due to a loading or regulation problem, but due to safety. This is
because the DC output winding may be part of the AC load winding, & that can
put DC onto the AC output or bypass some of the safety trip features, as well
as MAKE THE 230V NON FLOATING & therefore more hazardous! If you intend to use
both at once do at least use a ELCB/RDC mains trip plug!
Why Don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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