| |
G8MNY > TECH 11.09.04 22:22l 51 Lines 2068 Bytes #999 (0) @ WW
BID : 10300_GB7CIP
Read: GUEST OE7FMI
Subj: LCD Voltmeter Screwdriver
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<7M3TJZ<ZL2TZE<GB7YFS<GB7CIP
Sent: 040911/1901Z @:GB7CIP.#32.GBR.EU #:10300 [Caterham] $:10300_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (NEW Sept 2004)
ROLSTON ORIGINAL 1 VOLTMETER SCREWDRIVER
______________________________________
³gnd L C D ³
³ 220v 110v 55v 36v 12v ~ ³
Ą-Ā-----Ā-----Ā-----Ā-----Ā-----Ā----Ā-Ł<- Conductive Mats
DIRECT ³ ³ ³ ³ ³ ³ ³
ŪŪÄ22MÄÄ22MÄĮÄM92ÄĮÄM91ÄĮÄ1M2ÄĮÄ2M7ÄĮÄ10MÄĮÄÄÄÄ)ÄÄÄÄÄĀÄ=======>SCREWDRIVER
³ NEON
ŪŪÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĮÄ2M7ÄŁ
BREAK TEST
If you have not seen one of these, a small LCD panel in the handle indicates
the voltage is greater than the displayed graphics. This occurs when any of the
LCD sections sees greater than about 1V. As the LCD current required for this
is only the odd pA very high value resistors can be used to make up the
calibration multiplier chain. This means the return circuit can safely be made
though ones finger to earth.
A neon is also fitted for a BREAK TEST. (what ever that is)
N.B. in this circuit this is NOT such a safe option as current COULD flow
though the LCD to you!
G8MNY's MODIFIED VERSION
1/ Change one of the 22M to 10M to increase the sensitivity on DC.
2/ Then add a 270pF cap to reduce the sensitivity on AC.
3/ Add a 220K into the break test ciruit.
______________________________________
³gnd L C D ³
³ 220v 110v 55v 36v 12v ~ ³
Ą-Ā-----Ā-----Ā-----Ā-----Ā-----Ā----Ā-Ł<- Conductive Mat
DIRECT ³ ³ ³ ³ ³ ³ ³
ŪŪÄ22MÄÄ10MÄĀĮÄM92ÄĮÄM91ÄĮÄ1M2ÄĮÄ2M7ÄĮÄ10MÄĮĀÄÄÄ)ÄÄÄÄÄĀÄ=======>SCREWDRIVER
ĄÄÄÄÄÄÄÄÄÄÄÄÄ“ĆÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄŁ ³ NEON
270pF ³ ³
ŪŪÄÄÄÄÄÄÄÄÄ220KÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĮÄ2M7ÄŁ
BREAK TEST
Now Accurate from DC-50Hz
Why Don't U send an interesting bul?
/QSL
73 De John G8MNY @ GB7CIP
Read previous mail | Read next mail
| |
