IC697ACC721
IC697ACC721
IC697ACC721
IC697ACC721
本系统以AT89S52单片机为控制器，通过人机接口(按键和LCD显示屏)来设置输出电流，设置步进等级1mA，并可同时显示预设电流值和实际输出电流值。
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《邮@.com》本系统由按键设置输出电流值，经单片机计算后通过D／A转换器(TLV5618)输出模拟信号，再经过V／I转换电路转化成电流。单片机通过A／D转换器(MAX187)对采样电阻两端电压进行采样，经单片机处理，换算成电流值后显示在LCD屏幕上，供用户参考。实际测试结果表明，本系统输出电流可在20mA～1000mA范围内任意设定，精度±10mA，输出电流稳定，可应用于需要高稳定度、小功率恒流源的领域。
1、系统硬件结构
1．1系统原理
本设计采用模拟闭环控制。采用AT89S52单片机作为主控制器，用D／A转换器输出模拟电压信号，再经V／I转换电路获得电流。V／I转换电路依据电流串联负反馈原理，由运算放大器和大功率三极管组成模拟闭环，使输出电流稳定。
本系统可分为3个部分：电源部分、控制部分和V／I转换部分。电源不仅要提供±5V和±V供控制部分和V／I转换部分中的模拟器件使用，而且要提供大电压供V／I转换部分使用，且要有大功率输出的能力；控制部分的作用是根据用户设置值输出相应的电压信号；V／I转换部分的作用是把电压信号转化成相应的电流。各部分之间的关系如图1所示。
ABB Ulma KB2/A Keyboard AB Stromberg
ABB MINIATURE CIRCUIT BREAKER K 2A 3 POLE K2A
NIB ABB 10HP CONTACTOR STARTER B12-30-10 240V COIL N736
ABB MINIATURE CIRCUIT BREAKER K 8A 3 POLE K8A
ABB Contactor EHW250C2P-1L EHW250C2P1L New
ABB Size 5 Welding Isolation Contactor EHW-250WC-1L
ABB 25A 3pole Circuit Breaker NICE SHAPE CLEAN
ABB CIRCUIT BREAKER S271-K25A MINI CIRCUIT BREAKER
FITS ABB REVERSING CONTACTOR 120V COIL REV-EH145-120V
NIB ABB KB30-2/BRC30-2 240V COIL B25/B30 CONTACTOR N753
ABB CBK-KLTPT1R RED PILOT LIGHT 120V/6V NEW
ABB Circuit Breaker S222-K10A
ABB MODEL 0ETL200K3-2 LOAD BREAK SWITCH 200A NEW
ABB CBK-MPIR1WF1 PUSHBUTTON WHITE ILLUMINATED 120V NEW
ABB S272 K6A 277/480VAC 2 POLE CIRCUIT BREAKER
ABB MEM 86-192K + 192K RAM Memory DCG 3200-MR2
ABB AL9Z-30-10-15 Contactor, 24V-DC coil.
ABB MODEL CEL5-10 SIDE MNTG AUXILIARY CONTACT 1 NO NEW
ABB Circuit Breaker S271-K6A ~240/415V
ABB S271K10A 10A Circuit Breaker
NEW ABB FANUC MOD 300 BUS MODULE 6203FP10800 GENIUS
ABB CBK-LTPT1G PILOT LIGHT GREEN 120V/6V NEW
ABB Circuit Breaker S271-K6A
ABB 1200A MOLDED CASE SWITCH
NIB ABB TA42 DU-25 ADJ THERMAL HEATER (18-25A) N758B
ABB Circuit Breaker S271-K2A
ABB Type B Contactor B16-30-22 24-28V NIB __B59.1
ABB Switching Power Supply 24V CP-24/0.5
NIB ABB TA25 DU-25 ADJ THERMAL HEATER (18-25A) N742A
ABB S282-K10A CIRCUIT BREAKER
ABB Circuit Breaker S222-K8A
ABB/Kem Flow Meter ZHM 02/1 ST.E.T 73877-08
ABB Circuit Breaker, # S271-K6A, WARRANTY
NEW ABB FANUC MOD300 BUS MODULE 6203FP10900 GENIUS
ABB Circuit Breaker S271-K20A
NEW ABB FANUC TAYMOD 300 32PT MODULE 6241BP10411 GENIUS
FITS ABB REVERSING CONTACTOR 120V COIL REV-EH300-120V
ABB S272 K8A 400V 8A 2 POLE CIRCUIT BREAKER
Size 5 contactor ABB A260-30
FITS ABB REVERSING CONTACTOR 120V COIL REV-EH175-120V
NIB ABB K22-2 10A CONTROL RELAY K22E 2NC/2NO 240V N738
NIB ABB TP180IA 10-180SEC TIMER BLOCK FOR RELAY N751A
AB 1326AB-B515G-21 1326ABB515G21 SERVO MOTOR 460V
ABB Contactor Relay KC40E-01 24V DC
ABB S272 K20A 400V 20A 2 POLE CIRCUIT BREAKER
Macbook PRO 15" C2D A1211 2.33 Palmrest Trackpad ABB
ABB S272 K16A 400V 16A 2 POLE CIRCUIT BREAKER
ABB OS30AJ12P Disconnect Switch 30A
ABB S282 K16A 277/480VAC 2 POLE CIRCUIT BREAKER
ABB CBK-LTL1G GREEN LED LIGHT 120/24V NEW
NEW ABB T25 DU-32 ADJ THERMAL HEATER (24-32A) N740C
ABB S272 K2A 400V 2A 2 POLE CIRCUIT BREAKER
ABB CONTACTOR A110-30 COIL 110/120 50/60 HZ NIB
ABB EHDB 280 EHDB280C2P-1L 280A DC 120V coil
ABB S3L100MW Circuit Breaker
ABB Control D.O.L. Motor Starter on Base DLA9-30-84
ABB CIRCIUT BREAKER ESB63020L 20 AMP 3 POLE NIB
NEW ABB 10A DIN 1P CIRCUIT BREAKER M/N S281-K10A N809
ABB S272 K25A 400V 25A 2 POLE CIRCUIT BREAKER
NEW FITS ABB/ASEA 120V COIL KH550-1 EH370/450/550-120V
NEW ABB POWER SUPPLY Model CP24/5.0 OEM 1SVR423416R0000
ABB MODEL PCU-03 PURGE CONTROL BOARD PCU03 NEW
ABB CIRCUIT BREAKER FAL34015
NEW FITS ABB/ASEA COIL KHV CO-EH0V
ABB MODEL OESA250DV12PL1 SWITCH FUSE 250A NEW
ABB OK50FC Fast Contactor 50A OKX-OG11-U/50A
ABB S272 K40A 400V 40A 2 POLE CIRCUIT BREAKER
ABB CIRCUIT BREAKER ESB23020L 240v 20a 3PHASE
AC Adapter/Power Supply Cord for HP/Compa#ABB
ABB MODEL E-32215 APMXB03 CARD MODULE NEW
ABB MODEL EH170AC CONTACTOR 300A 3 POLE NEW
BRAND NEW ABB 30MM PROXY
ABB ELFG-315 CONTACTOR 360A 500VAC/500VDC 200HP NIB
ABB, TYPE JS CIRCUIT BREAKER, 300 A, 500 VD
NIB ABB 16A DIN 2P CIRCUIT BREAKER F362-16/0.01 N812
ABB OVER LOAD RELAY NEW CAT#ISAZ11-
ABB MINIATURE CIRCUIT BREAKER B 25 2 POLE B25
ABB 279410A04, 2.8KV, 65A, 50K, COL Capacitor Fuse
ABB MS 325 MS325 690V Manual Motor Starter
ABB JSS63400L 400 Amp 3P 600V 10KAIC
ABB STARTER CONTACTOR A26N NEW A26N13084