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A battery operated 4-20mA, using efficient switching method instead of linear circuit. Actually it works in 0-24mA (-25% to 125%) range.
The main components are:
- AT89C2051, 2kbyte flash mcu
- LPH7366, also known as Nokia 5110 LCD
- DAC7611, 12-bit serial input DAC
- TL494, pulse width modulation control circuit
- B0524LS, 5V to 24V DC/DC converter
- 1200mAH rechargable battery.
This is the internal view of the circuit.
There are 2 pcb, one for display and another one for main circuit. Both pcbs are linked with two bus connectors at top and bottom sides.
The connector at the bottom is used for charging battery by an external charger.
The component pinout.
Hex code:
:03000000020551A5
:0C055100787FE4F6D8FD75810E02059855
:100003004D410020202020202020002D0020002E04
:10001300002500535344414F00535445503100537E
:100023005445503400494E26415554004A494E47E1
:1000330055490019120C0600060C12191F252B3204
:10004300383E444B51575D646A70767D004B3219DC
:100053000019324B0019324B0019324B0019324B45
:100063000019324B00000000000000005F00000098
:1000730007000700147F147F14242A7F2A122313F6
:1000830008646236495522500005030000001C2213
:1000930041000041221C0014083E081408083E08D1
:1000A30008005030000008080808080060600000DD
:1000B30020100804023E5149453E00427F40004261
:1000C300615149462141454B311814127F10274590
:1000D3004545393C4A4949300171090503364949C7
:1000E3004936064949291E003636000000563600B7
:1000F300000814224100141414141400412214089B
:100103000201510906324979413E7E1111117E7F68
:10011300494949363E414141227F4141221C7F49A1
:100123004949417F090909013E4149497A7F080844
:10013300087F00417F41002040413F017F08142296
:10014300417F404040407F020C027F7F0408107FC4
:100153003E4141413E7F090909063E4151215E7FEF
:1001630009192946464949493101017F01013F40A7
:1001730040403F1F2040201F3F4038403F6314084A
:10018300146307087008076151494543007F4141E3
:100193000002040810200041417F00040201020410
:1001A3004040404040000102040080F0F8FCFEFFA4
:1001B30007030307FFFEFCF8F080FFFFFFFFFFFFCD
:1001C30000000000FFFFFFFFFFFF00071F3F7FFF4F
:1001D300E0C0C0E0FF7F3F1F0700001018181CFE9F
:1001E300FEFFFFFF0000000000000000000000FF12
:1001F300FFFFFFFF000000000000008080C0E0FF61
:10020300FFFFFFFFE0C0808000006070381C0E0F0E
:100213000F0F1F3F7FFEFEFCF000000000000000F8
:100223000080C0E0703F1F070100C0E0F0F8FCFE53
:10023300FFFBF9F8F8F8F8F87C3E0010180C0607F5
:100243000707070FFFFFFE7C3800000000000004D3
:10025300040E1E3F7FFFFCF8F0E0387C7CFCF8F0D6
:10026300E0E0E060703F3F1F0F070000000080C028
:10027300E070F8FEFFFFFF000000F0F89C8E87811E
:100283008080FFFFFFFFFF808080070707070707C6
:100293000707FFFFFFFFFF07070700C0F87E1F1FC9
:1002A3001F1F1F1F1F1F1F0F03010E0F0F0F0F1FF6
:1002B3001F1F3F3F7EFEFCF8F0003078F8F8F0E0B7
:1002C300E0C0C0C0C0E0713F1F000000C0E0F0F814
:1002D3007C1C0E0E070703030101F8FFFFFFFF0F4E
:1002E3000C0C0C1C7CFCF8F0C000071F3F7F7FF058
:1002F300C0C0C0C0F07F3F1F07007E3F1F0F0F0F1E
:100303000F0F0F0F0FEFFF3F0F0300000000000060
:100313000000C0F87F0F010000000000000000C0D3
:10032300F0FE1F03000000000000F8FCFEFEFFC704
:100333008303030307FFFEFCF80081C3E7EFFF3FDE
:100343003F7FFEFEFFFBF3E1C0001F3F7FFFE0C0E6
:10035300C0C0C0E1FF7F7F3F0F00F0FCFEFEFF0F38
:100363000303071FFEFEFCF0C000030F1F1F3F3CEB
:10037300303030F0FFFFFFFF1F0000C0C0C0E0F0CF
:0A038300783C3E1F0F070300000046
:06079A00010E02010D003A
:10074B00E4FDFCC3ED9FEC9E500DE4FB0BBBC8FC22
:07075B000DBD00010C80EC54
:010762002274
:100789007E08C292EF339291D292EF25E0FFDEF21A
:01079900223D
:0507A100C2900207896F
:0F076300F583E5822AF582E43583F583E493FF7D
:05077200D2900207898E
:10077700EF547F2480FF1207A1ED54072440FF02A6
:0207870007A1C8
:0E064800E50875F00A8485F009E5092430FF05
:10065600EFC39420402EEFD3947F5028EF75F0051A
:10066600A42460FFE5F034FFAD07FC7B0574682D1C
:10067600F58274003C12076D0DBD00010CDBEEE443
:04068600FF120772E6
:01068A00224D
:0606CC007BFF7A00790EAD
:1006D2008B0A8A0B890CAB0AAA0BA90C120732FFF0
:1006E20060101206567401250CF50CE4350BF50B5F
:0306F20080E4227F
:10071900E4FDFF1207777DF87C01E4FF120772ED13
:080729001D70011CED4C70F283
:0107310022A5
:10068B00D293C2937F647E0012074BD29312074B17
:10069B007F211207A17FC81207A17F061207A17F36
:1006AB00131207A17F201207A17F0C1207A11207BB
:1006BB00197F081207A17F0C1207A1E4FDFF0207A7
:0106CB0077B7
:0405DD00AC07AB05B7
:1005E100EB1475F011A4FF7D02120777E4FA75F0A0
:1005F10030ECA424CDF582E5F034011207630ABA88
:1006010010ECEB1475F011A4FF7D01120777E4FAE9
:1006110075F030ECA424BDF582E5F03401120763D6
:100621000ABA10ECEB1475F011A4FFE4FD12077780
:10063100E4FA75F030ECA424ADF582E5F034011252
:0606410007630ABA10EC89
:010647002290
:1006F500E50D75F069A4FBAAF07D01EAA2E392B3CA
:10070500EB25E0FBEA33FAC2B4D2B40DBD0DECC261
:03071500B2D2B2AB
:0107180022BE
:10038D00E50D75F00A84FF7D011205DDE50D75F0B3
:10039D000A84AFF07D021205DD7D027F23120777FF
:1003AD007BFF7A0079031206D2E4FD7F2A120777CC
:1003BD007BFF7A0079061206D2E4FD7F2A120777B9
:1003CD00E50D90003693FFF50875F06484F509EF9F
:1003DD00D3946340051206518015E50DC394035067
:1003ED00051206CC80097BFF7A0079101206D2E542
:1003FD000875F0648485F008E50875F00A84F50940
:10040D00E50D90003693D3940940051206518013E3
:10041D00E50DB403051206CC80097BFF7A00791037
:10042D001206D21206487BFF7A0079121206D2E527
:10043D000D90004F93F50875F00A84F5092430FFEF
:10044D001206561206487BFF7A0079141206D27DE9
:10045D00057F361207777BFF7A0079161206D27D5B
:10046D00047F36120777E50EB4010B7BFF7A007916
:10047D001C1206D280097BFF7A0079221206D27DEA
:10048D0004E4FF1207777BFF7A0079281206D27DEC
:0F049D0005E4FF1207777BFF7A00792F0206D262
:1004AC0012068B120719D2B2D2B3D2B412038D1228
:1004BC0006F53095FD3094FD3096FD7F147E0012CC
:1004CC00074BA2948295829640F820960DE50EB4C7
:1004DC000105750E028003750E01209520E50EB402
:1004EC000104050D800DE50D1313543F0425E02583
:1004FC00E0F50DE50DD394184003750D18209435D7
:10050C00E50EB4010BE50DD394004029150D8025A3
:10051C00E50DC39404401BE50D54036006740425DB
:10052C000DF50DE50D1313543F1425E025E0F50DE5
:10053C008003E4F50D12038D1206F57F147E001274
:05054C00074B0204BE94
:10055D000204ACE493A3F8E493A34003F68001F204
:10056D0008DFF48029E493A3F85407240CC8C3339F
:10057D00C4540F4420C8834004F456800146F6DF6E
:10058D00E4800B010204081020408090079AE47E5D
:10059D00019360BCA3FF543F30E509541FFEE49363
:1005AD00A360010ECF54C025E060A840B8E493A32A
:1005BD00FAE493A3F8E493A3C8C582C8CAC583CA55
:1005CD00F0A3C8C582C8CAC583CADFE9DEE780BE0D
:0107A0000058
:10073200BB010689828A83E0225002E722BBFE02C5
:09074200E32289828A83E49322F8
:00000001FF
TODO: Schematic
