Ton Giesberts
About the article

Campsite AC Monitor

“I packed my bag and in it I put…”

Campsite AC Monitor
Those of you who go camping regularly will have experienced this before: you switch on a powerful electric hob just when the fridge is on and the campsite fuse blows. It’s a pain because the campsite manager usually has to be called to replace or reset the fuse and the excercise can cost a lot of money. This campingsite AC monitor makes these occurrences a thing of the past.
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Extra info / Update

Technical specification
- For 230 VAC or 120 VAC campsite power lines
- Limits at 3 A, 4 A, 5 A, 6 A, 7 A, 8 A or 10 A
- Indicator LED
- Activation level configurable by jumper or rotary switch



June 8th, 2009.

In the component llst D5 should be 5.6 V, not 2.7V. The value is correctly indicated in the published schematic.

Component list
Caution. Circuit designed for 230 VAC power lines. Please refer to circuit description for component adaptation to suit 110-120 VAC networks.
R1,R2 = 4kO7 5W, lead pitch 30mm max.
R3,R4 = 330k
R5,R23 = 100
R6,R24 = 100k
R7,R8 = 0O1 5W, lead pitch 30mm max.
R9 = 20kO0
R10 = 10kO0
R11 = 30kO1
R12 = 1kO91
R13,R14,R17 = 698
R15,R16 = 715
R18 = 1kO40
R19 = 100k
R20 = 10k
R21 = 3kO3
R22 = 1M
R25 = 820k
R26 = 1k
P1 = 100kO preset
C1 = 1µF 63V, radial, lead pitch 2.5mm, diam. 6.3mm max.
C2 = 10nF lead pitch 5mm or 7.5 mm
C3,C6,C10 = 100nF, lead pitch 5mm or 7.5mm
C4 = 220µF 25V, radial, lead pitch 2.5mm, diameter 8.5mm max.
C5 = 220nF 275VAC X2, lead pitch 22.5mm
C7 = 10µF 63V, radial, lead pitch 2.5mm, diam. 6.3mm max.
C8 = 1nF, lead pitch 5mm or 7.5mm
C9 = 22µF 40V, radial, lead pitch 2.5mm, diam. 6.3mm max.
L1 = 22µH 11A e.g. 1422311C Murata Power Solutions (Farnell order code 1077056)
22µH 10.3A e.g. 2205-V-RC (J.W.Miller Magnetics), Digi-Key # M8868-ND
D1 = 1N4007
D2 = 4.7V 0.5W zener diode
D3,D4,D7 = BAT85
D5 = 5.6V 0.5W zener diode (corrected value)
D6 = red low current LED
T1 = BF245A
TRI1 = BTA16-600BWRG (TO220AB insulated) (Farnell # 1175636)
IC1 = U2008B (Atmel), 8-pin DIP
IC2 = TS922IN (ST), 8-pin DIP
K1 = 14-way (2x7) pinheader + 1 jumper
F1 = 10A 1¼” x ¼” e.g. Farnell # 1175149 + 2 fuse clips 15A rated, Farnell # 1175125
4 AMP connectors , M4 screw mounting, + 4x 10 mm M4 bolt + nut + washer + locking ring
Ceramic isolation 4.5mm e.g. type AOS220SL (Fischer Elektronik)
Heatsink for 10A: Rth < 3.7 K/W (< 9.4 K/W voor max. 6A)
PCB # 060316-1 from
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