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G8MNY > TECH 11.03.24 13:50l 90 Lines 4248 Bytes #999 (0) @ GBR
BID : 2428_GB7CIP
Read: GUEST
Subj: Maplin Mains Meter 2000MU-UK
Path: ON0AR<IW0QNL<VE2PKT<PD0LPM<MM0RJJ<GB7YEW<GB7COV<GB7CIP
Sent: 240301/0824Z @:GB7CIP.#32.GBR.EURO #:2428 [Caterham Surrey GBR] $:2428_GB
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@GBR
By G8MNY (Updated Mar 10)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
This plug in meter is made by Prodiget Electronics Co for Maplin.
It measures true RMS:- Frequency, Voltage, Current, VA, Power Factor, & kWHrs
to quite a high accuracy. Current over 16A sounds an alarm.
.컴컴컴컴. 旼컴컴컴컴컴컴�
Inside there are 2 PCBs 넷rib'd�||L 납~~~~~~~~~~~납
with SMD components & 넷m i�||C 납 납
an IC on each, they are 넷e s�||D 납 납
joined by short soldered 넷a p� � 냅컴컴컴컴컴켸�
in ribbon cable. 넷s l梭� mode � � � � � � �
넷u a泗� buttons � � � � � � �
The measuring PCB 넷r y� � 놈拙拙拙拙拙�
includes the series _넷e ___� 넬컴컴컴컴커�
dropper PSU. 複複� � � � 납 � 납
栢栢� � � � 13A 납 � 납
The display PCB has the � � � � socket 납 납
processor mode buttons 複屛 � � � 납 複 複 납
& display drive. 13A 읕� 읕컴� 납_________납
Plug 읕컴컴컴켸 읕컴컴컴컴컴�
PRINCIPLE
Once in digital form, the instantaneous voltage & currents can easily be number
crunched in the uProc to measure & display the Voltage, Current, Frequency,
True RMS power Watts, VA, Power Factor, & kW Hours.
旼컴� 旼컴컴� 旼컴컴컴커
Current 퀮-D쳐캑uProc쳐캑Display �
Volts 컴� � � 쳐캑 & �
읕쩡� 읕컴쩡� 쿎ontrols�
Ref Timebase 읕컴컴컴켸
CIRCUIT
E컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴E
Mains Mains
Plug Socket
N L N L
� 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�)컴컴�
읕컴컴컴컴컴컴컴컴컴컴쩡R20컴컴쩡컴컴컴컴컴컴� �
� Link R15 o
N� 1k115 |fuse
旼풮ad旼컴컴컴� 旼좔컴컴컴컨컴커 R16 o200mA
쿗췻拙� 췻拙拙蹄 Ref I V쳐컴컴1M0컴컴컴�
쿎췻拙� 췻拙拙蹄 Measure IC � ===C6
쿏췻拙� � 읕쩡컴쩡컴컴컴켸 � 0.68uF
읕� � 쿝ibbon 쿙 �+5V R18
Volto\_� uProc � � � 旼컴컴� 100
읕캑 쳐컴컴컴�)컴컨컴�78L05쳐쩡컴컫캑<쳐컴�
Amp o\_� IC � � 읕컫컴� � � _�_
읕캑 쳐커 � � _�_ � /_\
W/VAo\_� � Xtal � � /_\' +�100u �
읕캑 쳐켸 � � 17V� ===C2 � R20 cal for I
F/PFo\_� 쳐커 � � � � � R16 cal for V
읕캑 � Buz � � � � � (HV rated!)
KW o\_� 쳐컨컴컴컨컴컴컴컴컨컴컴좔컴컨컴컴컴켸
읕캑_______�
IMPROVEMENTS
1/ The unit is not to be used outdoor (not water proof) & the internals are
live. I syringed in "copydex" rubber solution over all the case joints &
cracks, including the plug, socket & LCD surround. Although not perfectly
water proof it is a lot safer in outdoor use.
2/ R18 100R 5W surge R came unsoldered when measuring inverter square wave.
Replaced with 660� (2x 330R 5W) using the unused solder lands available.
This ensures less peak current on non sine wave sources. I also added a
solder tags as a heatsinks to each end of the 17V zener connections.
3/ Added a small white LED to the side of the LCD, with a tin foil as opposite
end reflector. The 3.5V LED runs across the zener supply via a 1k. So the
meter is usable at night. This also indicates if there is power, but the
uProc has crashed (needs repowering).
See my buls on "AC Theory", "Constant Voltage Transformers", "Variacs",
"Portable Appliance Testing", "UK 13A Fused mains plug", "Mains Power
Protection" & also "Maplin 13A Socket Mains Tester".
Why don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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