3 7 khz optical chopper controller

{"cid":"91217181","title":"SRS Stanford Research Systems SR540 Optical Chopper Controller with 4 Hz to 3.7 kHz Range, 4-Digit Frequency Display and GPIB, RS-232, Ethernet Interfaces","imgUrl":"https:\/\/img.chinax.com\/nimg\/71\/dd\/f80858757e241387847c129c5700-200x200-1.jpg","attrs":{"Price":"Negotiation","Brand Name":"SRS","Model Number":"SRS540","Minimum Order Quantity":"1 set","Place of Origin":"USA","Payment Terms":"T\/T","Supply Ability":"in stock","Product name":"Optical Chopper Controller","Chopping frequency":"4 Hz to 3.7 kHz","Frequency display":"4-digit, 1 Hz resolution and accuracy","Cable length":"6 ft.","Power":"12 W, 100\/120\/220\/240 VAC, 50\/60 Hz","Interfaces":"GPIB, RS-232 and Ethernet"}}