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The statements in questionare towards the end of the“Safety” section of the article.To say that the parts could gobang (i.e., explode) and thento suggest the circuit is put ina box is rather unprofession-al to say the least. In circuitslike this you must put in adevice (e.g., slow blow fuse)that is designed to limit cur-rent and prevent a partexploding. DO NOT just tryto contain the explosion in abox! Ideally this fuse needs tobe near the battery and allconductors must be able tocarry the fuse blow current. Iexpect a 5 amp slow blowfuse (or Polyswitch) would beable to cope with the short40-A pulse, but you need tocheck this.
Clearly you have not seenthe damage that an explod-ing high wattage resistor cancause, I’ve seen holespunched through 0.8-mmthick steel from shards offresistors (caused by a ran-dom failure and sloppydesign practice!). Do yourdesigners expect readers tohave the circuit fully enclosedin a box when testing it forthe first time? Surely the firsttime it is switched on is themost likely time of failure!How is the reader supposedto check the voltages, as sug-gested, if it is not workingand in a box! Replacing R8with a high value (eg 100R)during test would be a goodapproach. A good designer
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thinks about how to test a cir-cuit and how to test it safely!I also question the wiregauge used in the harness inthe picture, this would surelymelt if the circuit failed.Incidentally I do like the newmagazine style and… I’vebeen reading Elektor since1975!Alan (UK)
You are absolutely right and weapologize for having overlookedthe safety aspects of the project tothe extent indicated. Most, if notall, problems may be solved byusing a 1-A slow-blow fuse nearthe battery. In-line fuses andmatching fuse holders as used incars are suitable.
Connector parts (2)Hello Jan — I too had a longsearch to find the type ofconnector (single pole) thatRichard Austin describes inMailbox, December 2004. Infact I get them from Farnell— although as Mr Austinfound, they do not believethey sell them! I have evensuggested to Farnell that theyinclude the item in the con-nectors and/or test sections,as well as in theSemiconductor hardwaresection where they are to befound.Look at page 522 of theBook 2 (May 2004) - OrderCode 518-025, but they arenot cheap! Hope this helps.Ian King (UK)
Thanks for your reply. Unfortu-nately, our design engineers say
that the connector you describeis not the one they (and Mr.Austin) are looking for. Thesearch continues...
Improved AtmelispIn last November’s Mailbox Iread a question on readingAT micros. I would like toadd that I have produced aversion of Atmelisp that offersadditional functionality, whilealso allowing BASIC andBASIC-52 programs to bedownloaded and uploaded.The program employs eithertwo conventional serialports or one USB and oneRS232 port, where the USBport is used for data com-munications via a USB/seri-al converter.My program has been testedon Windows 98, ME and XPHome Edition. I am offeringto supply the binaries to inter-ested readers.Piet van der Wal(Netherlands)
Interested readers may requestMr. van der Wal’s contact detailsby sending an email [email protected],subject: atmelisp
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The P89LPC900 (2)November 2003, p. 30-35;030161-2In the circuit diagram and onthe PCB, the RTS line is con-nected to pin 9 of 9-way sub-D connector K6. However,RTS should be connected topins 7 and 8. The PCB layouthas been modified accord-ingly (free download fromour website).
Simple Infrared ControlExtender(July/August 2004, p. 56;030103-1In the circuit diagram, T1should be a type BD241, notBD240. The circuit symbol(npn) is correct.
Multi Programmer onUSBJune 2004, p. 10-16In the parts list on page 16,IC4 should read 74LS07, not74LS04.
CORRECTIONS &UPDATES
Slave Flash for DigitalCamerasOctober 2004, p. 58-60;040224-1The parts list should be cor-rected to readR1 = 3kΩ3R11 = 68kΩT4 = BC556
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