OPERATING INSTRUCTIONS AND SYSTEM DESCRIPTION FOR
Contents
1. L Set the MODE OF OPERATION switch to OFF Important The tuning procedure must not be done in VC mode _ Connect the electrode connector of the TEC B 01 headstage to ground If parasitic oscillations occur use a 10 kQ resistor for grounding _ Switch the digital display 9 to Vcer potential output of the current electrode using switch 10 Set the reading of the display to 0 using the OFFSET potentiometer 11 L After tuning the current electrode potential OFFSET simulate an electrode by replacing the 10 kQ resistor with a much larger resistor e g 1 MQ L The digital display and the CURRENT ELECTRODE potential connector CEL x10mV 18 now shows a voltage deflection that is related to the BIAS current of the headstage according to Ohm s Law Cancel this voltage by tuning the BIAS Cz trim pot 12 The current is 0 if the voltage deflection is 0 Note Due to the characteristics of the high voltage OPs the Vcg display may fluctuate around the baseline of 0 mV by some mV With a 1 MQ resistor as used in the cell model 1 mV corresponds to 1 nA Keeping in mind that the display accuracy of the current is 10 nA in the last digit this is insignificant Important The bridge amplifier it has a BIAS current as well and must be adjusted as described in the bridge amplifier user manual 13 CAP COMP potentiometer Control for the capacity compensation of the CURRENT electrode or the signal connected to the EXT IN2. D Electronic A Instruments for the Life Sciences pease ade O OPERATING INSTRUCTIONS AND SYSTEM DESCRIPTION FOR THE TEC B 01 VOLTAGE CLAMP UNIT FOR BRIDGE AMPLIFIERS scaled for use in leech neuron experiments VERSION 1 0 npi 2011 npi electronic GmbH Hauptstrasse 96 D 71732 Tamm Germany Phone 49 0 7141 9730230 Fax 49 0 7141 9730240 support npielectronic com http www npielectronic com TEC B 01 User Manual Table of Contents le Safety RegulatioHs code E etn hc aye ae al a Gc Sas 3 2 FECSB 0 Irrien edite a i ee RU a lg de cl a i cei RD e OE 4 2 Ls Components PRETI M R 4 2 2 System DOSCPIDUOI oerien tO densa Gr He aE Mut ae Disi Cerat E EKE ASE SA 4 2 5 Description of the Front Panel 2 2 site eel oi inet dee etoile nite 4 Current Headstage Bias Current Adjustment for TEC B 01 esses 7 T ning procedure se oio erepti eret ees e aa aa ley stad eae Codva iion 7 2 4 Description of the Rear Panel eese ceo tee ein ta etras er eene e sucsaaeadageceda weds 9 SES OU PREDA 9 Ss Stand AOne Operation o trente opas a a a oases acte meee 9 3 2 Operation with Bridge Amplifier 5 reet tet en Penne et ane AE SERIE Pena eU aes 9 Ae Simple Cell model oe oe per tirare tavecavendedaesy Epi Utt teste bati a e acted pid ius Raus tm 10 AT COCR DIMUS LR vp Cu 10 5 Techical DIU uices cuoi ptt ecd a a amener clc Rr cmt 10
3. version 1 0 page 2 TEC B 01 User Manual 1 Safety Regulations VERY IMPORTANT Instruments and components supplied by npi electronic are NOT intended for clinical use or medical purposes e g for diagnosis or treatment of humans or for any other life supporting system npi electronic disclaims any warranties for such purpose Equipment supplied by npi electronic must be operated only by selected trained and adequately instructed personnel For details please consult the GENERAL TERMS OF DELIVERY AND CONDITIONS OF BUSINESS of npi electronic D 71732 Tamm Germany 1 2 3 4 5 GENERAL This system is designed for use in scientific laboratories and must be operated only by trained staff General safety regulations for operating electrical devices should be followed AC MAINS CONNECTION While working with npi systems always adhere to the appropriate safety measures for handling electronic devices Before using any device please read manuals and instructions carefully The device is to be operated only at 115 230 Volt 60 50 Hz AC Please check for appropriate line voltage before connecting any system to mains Always use a three wire line cord and a mains power plug with a protection contact connected to ground protective earth Before opening the cabinet unplug the instrument Unplug the instrument when replacing the fuse or changing line voltage Replace fuse only with an appropriate specified type STATIC ELECT
4. connector 16 potentiometer with OFF position clockwise 14 Current HEADSTAGE connector Connector for the current headstage 15 COMMAND IN 10 mV connector BNC connector for an external COMMAND voltage in VC mode sensitivity 10 mV The signal form remains unchanged 16 EXT IN 1 pA V connector BNC connector for connecting an external voltage signal This can be used to operate the TEC B 01 module as a constant current source e g for iontophoresis Scaling is 1 uA V i e 100 mV connected at EXT IN leads to a current of 100 nA at the current electrode 17 CURRENT OUT connector BNC connector providing the current signal The scaling is set by switch 5 The filter is set by switch 4 18 Cg x10 mV connector BNC connector providing the potential of the current electrode version 1 0 page 8 TEC B 01 User Manual 19 ms INTEGRATION potentiometer The integrator improves control performance for slower signals Position OFF disables the integrator Setting a time constant by turning the potentiometer clockwise converts the controller into a PI proportional integral system Time constant range is 10 0 1 ms 2 4 Description of the Rear Panel A cable is firmly connected for linking the TEC B 01 amplifier to the bridge amplifier connector TO TEC B 01 at the rear panel of the bridge amplifier CHASSIS This connector is linked to mains ground green yellow wire protective earth GROUND This connecto
5. mode 7 0 switch Switch for setting the polarity of the HOLDING POTENTIAL in VC mode In 0 position the HOLDING POTENTIAL is disabled i e set to 0 mV 8 DUAL LED LED indicating operation with the a bridge amplifier in CC or VC mode version 1 0 page 6 TEC B 01 User Manual 9 Display LED display for the CURRENT passed through the CURRENT electrode in uA XX XX uA switch 10 in Icgr position or the potential at the current electrode in mV XXXX mV switch 10 in VceL position or the resistance of the current electrode XX X MQ switch 10 in Rcg position 10 Veg Ice Rcg switch 3 position switch for selection of the display mode Vcg potential of the current electrode is displayed Icer current value is displayed Rcg resistance of the current electrode is displayed 11 OFFSET potentiometer 10 turn potentiometer to cancel potential OFFSETS at the current electrode 12 BIAS Cg trim pot Trim pot for adjusting the current headstage BIAS current Current Headstage Bias Current Adjustment for TEC B 01 Caution It is important that this tuning procedure is performed ONLY after a warm up period of at least 30 minutes The tuning procedure should be performed regularly at least once a month with great care since the bias current changes over time and it determines the accuracy of the TEC BA system The TEC B 01 is equipped with a current source that is connected to the current injecting elect
6. RICITY Electronic equipment is sensitive to static discharges Some devices such as sensor inputs are equipped with very sensitive FET amplifiers which can be damaged by electrostatic charge and must therefore be handled with care Electrostatic discharge can be avoided by touching a grounded metal surface when changing or adjusting sensors Always turn power off when adding or removing modules connecting or disconnecting sensors headstages or other components from the instrument or 19 cabinet TEMPERATURE DRIFT WARM UP TIME All analog electronic systems are sensitive to temperature changes Therefore all electronic instruments containing analog circuits should be used only in a warmed up condition i e after internal temperature has reached steady state values In most cases a warm up period of 20 30 minutes is sufficient HANDLING Please protect the device from moisture heat radiation and corrosive chemicals version 1 0 page 3 TEC B 01 User Manual 2 TEC B 01 2 1 Components The following items are shipped with the TEC B 01 system TEC B 01 amplifier Headstage Ground connector for headstage 2 6 mm Power cord User manual SSSAS Optional accessories Electrode holder Electrode holder adapter for mounting to a micromanipulator elec D Passive cell model 2 2 System Description The TEC B 01 amplifier module is designed to be used together with a modified BA 1S BA 01X or BA 03X bri
7. dge amplifier In two electrode CC or VC mode the current is applied through the current electrode connected to the TEC B 01 and potential measurement is performed through the bridge amplifier The active connection of the two amplifiers is indicated by the DUAL LED The bridge amplifier has also an LED besides the display indicating two electrode operation It is also possible to use the bridge amplifier as usual only with the electrode connected the BA 1S BA 01X or BA 03X For operation of the bridge amplifier using only one electrode the MODE OF OPERATION switch of the TEC B 01 has to be set into EXT or OFF position In EXT position the TEC B 01 can be used as current pump e g for iontophoresis 2 3 Description of the Front Panel In the following description of the front panel elements each element has a number that is related to that in Figure 1 The number is followed by the name in uppercase letters written on the front panel and the type of the element in lowercase letters Then a short description of the element is given version 1 0 page 4 TEC B 01 User Manual Figure 1 front panel view of the TEC B 01 version 1 0 page 5 TEC B 01 User Manual 1 MODE OF OPERATION switch Switch to select the MODE OF OPERATION VC Voltage Clamp OFF In this position the current injection of the amplifier is switched OFF e g for operating the bridge amplifier as stand alone device CC Current Clamp with current injectio
8. ier headstage is used for potential measurement Current headstage Operating voltage 45 V Input resistance gt 10 Q Electrode connector BNC shield is grounded Ground 2 4 mm connector or headstage enclosure Size 23 x 70 x 26 mm enclosure grounded Holding bar diameter 8 mm length 10 cm Current range 450 nA 100 MQ or 4 5 uA 10 MQ Current electrode parameter controls Offset compensation ten turn control 1200 mV Electrode Resistance Test obtained by application of square current pulses 10 nA display XX X MQ selected by switch Current Outputs Filtered output sensitivity set by current range switch with low pass Bessel filter output impedance 50 Q Current range switch 1 uA V 10A V or 100 uA V DISPLAY XX XX uA Current Output Filters One pole low pass Bessel filter 6 corner frequencies 100 300 500 1k 3k or 5k Hz Current Clamp current stimulus input from bridge amplifier Inputs 100 nA V Input impedance gt 100 KQ HOLD X XX uA ten turn digital control with 0 switch maximum 1000 nA Voltage Clamp Input sensitivity 10 mV Input impedance gt 100 KQ HOLD XXX mV ten turn digital control with 0 switch maximum 1000 mV version 1 0 page 11
9. n through the current headstage Note In CC operation the current stimulus input of the bridge amplifier is used EXT EXTernal control For operating the TEC B 01 amplifier as a constant current source e g for iontophoresis or for operating the bridge amplifier as stand alone device POWER OFF Power is turned OFF 2 GAIN VC potentiometer 10 turn potentiometer to set amplification factor GAIN of the VC error signal To keep the VC error as small as possible it is necessary to use high GAIN settings but the system becomes unstable and begins to oscillate if the GAIN is set too high 3 Rs COMP potentiometer 10 turn potentiometer to set the amount of series resistance compensation Series resistance compensation improves the performance of the clamp system especially if fast voltage activated currents are recorded Important Series resistance compensation is done by positive feedback in the control circuit which can lead very quickly to stability problems Therefore tuning of the series resistance compensation has to be carried out with great care 4 CURRENT FILTER Hz switch 6 position switch to set the corner frequency of the CURRENT FILTER 100 300 500 1k 3k or 5k Hz available at 17 5 CUR OUTP SENS V uA switch Switch to set the amplification of the current signal at 17 1 V uA 10 V uA 100 V uA 6 HOLDING POTENTIAL potentiometer 10 turn potentiometer for setting the HOLDING POTENTIAL in VC
10. r is linked to the internal system ground which has no connection to the 19 cabinet CHASSIS and the mains ground to avoid ground loops 3 Operation The TEC B 01 can be operated as a stand alone device or in conjunction with a modified bridge amplifier 3 1 Stand Alone Operation The TEC B 01 can be used as a current pump e g for iontophoresis The MODE OF OPERATION switch 1 Figure 1 A voltage signal is connected to the EXT IN BNC connector 16 Figure 1 This voltage signal is converted into a current signal with a scaling of 1 uA V The mostly rectangular shape of the input signal can be influenced by the capacity compensation 3 2 Operation with Bridge Amplifier Together with a modified bridge amplifier the TEC B 01 can be used for two electrode voltage clamp TEVC or two electrode current clamp TECC experiments The scaling is adapted for current ranges normally used in experiments in leech neurons For two electrode operation the TEC B 01 and bridge amplifier are connected with a cable at the rear panel The operation mode switch 1 Figure 1 is set to CC for current clamp or VC for voltage clamp The current electrode is connected to the TEC B 01 headstage and the potential electrode to the headstage of the bridge amplifier Since in leech neurons usually the x10 voltage range the bridge amplifier is automatically set into the x10 mode if functionally connected to the TEC B 01 In two electrode operation curren
11. rode and performs the current injection This current source has a high impedance floating output Therefore the zero point the zero of the BIAS current of the current source must be defined i e without an input signal there should not be an output current The tuning procedure is done using the BIAS Cg trim pot and one resistance of a few KQ and one of a few MQ It is based on Ohm s Law U R I If the headstage generates an output current this current will cause a voltage deflection at a test resistor If this test resistor has a low resistance of only a few kQ this voltage deflection originates only from a possible offset of the electrode that can be cancelled using the OFFSET Cpr 11 Figure 1 potentiometer Replacing the low resistance resistor by one of a much higher resistance may lead to another voltage reading at the digital display This voltage deflection then originates only from the BIAS output current and is proportional to this output current according to Ohm s law Using the BIAS Cg trim pot the monitored voltage can be set to 0 This cancels the BIAS current Tuning procedure The tuning procedure is performed using high value resistors It cannot be performed with an electrode since there are always unknown potentials involved tip potential junction potentials etc Warning High voltage Always turn power off when working directly on the current headstage output version 1 0 page 7 TEC B 01 User Manual
12. t injection is done with the current electrode connected to the TEC B 01 and potential measurement with the potential electrode This applies to both CC and VC modes Two electrode operation is indicated by the DUAL LED at the TEC 01 B as well as by the DUAL LED at the bridge amplifier version 1 0 page 9 TEC B 01 User Manual 4 Simple cell model A very simple cell model is also provided It consists of passive elements which simulate electrode resistances series resistance and capacity and resistance of the cell membrane Figure 2 simple cell model of the TEC B 01 BA system Electrode resistances 15 MQ for each electrode Rs switch ON OFF switch for setting a series resistance of 20 kQ C cell either with 100 kQ or 1 MQ membrane resistance membrane capacity is always 3 9 nF 4 1 Operation Connect the white cable to the core of the BNC connector of the TEC B 01 amplifier Connect the grey cable to the core of the BNC connector of the BA amplifier Connect the black ground cable to GND of one of the headstages Select the desired membrane resistance Select whether to mimic a series resistance or not O O O O 5 Technical Data Modes of Operation CC Current Clamp mode VC Voltage Clamp mode OFF Current and Voltage Clamp disabled BA amplifier operational EXT External mode MODE selection by rotary switch version 1 0 page 10 TEC B 01 User Manual Headstages Potential headstage Bridge amplif
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