v 20110115 2 C 40000 40000 0 0 0 title-B.sym C 48500 45900 1 270 1 cap-mylar.sym { T 49200 46100 5 10 0 0 90 2 1 device=CAPACITOR T 47800 46600 5 10 1 1 180 6 1 refdes=C_SAW T 49400 46100 5 10 0 0 90 2 1 symversion=0.1 T 48000 46200 5 10 1 1 0 0 1 value=45nF } C 48600 44200 1 0 0 gnd.sym C 49900 46800 1 180 0 pnp.sym { T 49300 46400 5 10 0 0 180 0 1 device=PNP_TRANSISTOR T 50000 46900 5 10 1 1 180 0 1 refdes=Q_DIS } C 48200 44500 1 0 0 npn.sym { T 48800 45000 5 10 0 0 0 0 1 device=NPN_TRANSISTOR T 48700 45000 5 10 1 1 0 0 1 refdes=Q_SINK } N 47000 45600 48000 45600 4 N 48000 45600 48000 45000 4 N 47000 45600 47000 45200 4 C 47000 44600 1 0 0 opa.sym { T 47200 46900 5 10 0 0 0 0 1 device=DUAL_OPAMP T 47200 46700 5 10 0 0 0 0 1 footprint=DIL 14 300 T 47200 47100 5 10 0 0 0 0 1 symversion=0.2 } C 46800 43700 1 90 0 resistor.sym { T 46400 44000 5 10 0 0 90 0 1 device=RESISTOR T 47300 44300 5 10 1 1 180 0 1 refdes=R_1/3 T 46800 43700 5 10 0 1 90 0 1 footprint=R025DOUBLE T 46900 43900 5 10 1 1 0 0 1 value=22K 1% } C 48900 47100 1 0 1 3v3.sym T 46700 49200 9 10 1 0 0 0 1 Opamps are 1/4 LM324N from 5V N 48000 45000 48200 45000 4 N 49400 47100 48700 47100 4 N 48700 46800 48700 47100 4 C 50800 46200 1 0 1 resistor.sym { T 50500 46600 5 10 0 0 0 6 1 device=RESISTOR T 50500 46400 5 10 0 1 0 6 1 refdes=R? T 50800 46200 5 10 0 1 0 6 1 footprint=R025DOUBLE T 50100 46500 5 10 1 1 0 0 1 value=2K2 } N 44600 43600 44600 46600 4 C 44500 43600 1 270 0 pot-bourns.sym { T 45400 42800 5 10 0 0 270 0 1 device=VARIABLE_RESISTOR T 44900 43000 5 10 0 1 270 0 1 refdes=R? } N 45200 43900 46200 43900 4 N 46200 43900 46200 43300 4 N 45200 43900 45200 43500 4 C 45200 42900 1 0 0 opa.sym { T 45400 45200 5 10 0 0 0 0 1 device=DUAL_OPAMP T 45400 45000 5 10 0 0 0 0 1 footprint=DIL 14 300 T 45400 45400 5 10 0 0 0 0 1 symversion=0.2 } B 44400 42600 2000 1500 3 0 0 0 -1 -1 0 -1 -1 -1 -1 -1 T 45000 42300 9 10 1 0 0 0 1 1/2 MCP4922 DAC N 46700 44800 47000 44800 4 N 46200 43300 46700 43300 4 C 44500 42200 1 0 0 gnd.sym N 45200 43100 45100 43100 4 C 46700 44900 1 180 0 resistor.sym { T 46400 44500 5 10 0 0 180 0 1 device=RESISTOR T 45900 45200 5 10 1 1 0 0 1 refdes=R_2/3 T 46700 44900 5 10 0 1 180 0 1 footprint=R025DOUBLE T 46300 45100 5 10 1 1 180 0 1 value=10K 1% } N 45800 44800 44600 44800 4 N 46700 44600 46700 44800 4 N 48700 45900 48700 45500 4 N 48700 45500 50200 45500 4 N 49400 45800 49400 45500 4 N 49400 47100 49400 46800 4 N 44600 42500 44600 42700 4 N 46700 43700 46700 43300 4 T 46700 48900 9 10 1 0 0 0 1 NPN: 2N3904, PNP: 2N3906 T 50500 40900 9 10 1 0 0 0 1 EXPONENTIAL CURRENT DAC / SAWTOOTH OSCILLATOR T 47100 43500 9 10 1 0 0 0 1 R_1/3 and R_2/3 set V_BE range of Q_SINK to 2/3 to 1 times V_REF T 45600 47600 9 10 1 0 0 0 1 I_REF = 1mA T 45500 47300 9 10 1 0 0 0 1 V_REF = 630mV T 47100 43200 9 10 1 0 0 0 1 For DAC=0, current is about I_REF / 4000 (8 times V_T) or 12 octaves C 43300 46400 1 90 0 resistor.sym { T 42900 46700 5 10 0 0 90 0 1 device=RESISTOR T 43000 46500 5 10 1 1 90 0 1 refdes=R_REF1 T 43300 46400 5 10 0 1 90 0 1 footprint=R025DOUBLE } C 44600 46100 1 0 0 npn.sym { T 45200 46600 5 10 0 0 0 0 1 device=NPN_TRANSISTOR T 45200 46600 5 10 1 1 0 0 1 refdes=Q_REF } C 43100 45200 1 0 0 gnd.sym N 43600 47200 45100 47200 4 N 43600 47200 43600 46800 4 C 43600 46200 1 0 0 opa.sym { T 43800 48500 5 10 0 0 0 0 1 device=DUAL_OPAMP T 43800 48300 5 10 0 0 0 0 1 footprint=DIL 14 300 T 43800 48700 5 10 0 0 0 0 1 symversion=0.2 } N 43200 46400 43600 46400 4 C 43000 47300 1 0 0 3v3.sym N 45100 47200 45100 47100 4 C 45200 47200 1 90 0 resistor.sym { T 44800 47500 5 10 0 0 90 0 1 device=RESISTOR T 44900 47300 5 10 1 1 90 0 1 refdes=R_REF T 45200 47200 5 10 0 1 90 0 1 footprint=R025DOUBLE } C 44900 48100 1 0 0 3v3.sym C 45000 45800 1 0 0 gnd.sym C 43300 45500 1 90 0 resistor.sym { T 42900 45800 5 10 0 0 90 0 1 device=RESISTOR T 43000 45600 5 10 1 1 90 0 1 refdes=R_REF2 T 43300 45500 5 10 0 1 90 0 1 footprint=R025DOUBLE } T 41400 48100 9 10 1 0 0 0 2 Temperature stable reference (possibly drive set point from DAC) N 50200 44700 51200 44700 4 N 50200 44700 50200 45100 4 C 50200 45700 1 180 1 opa.sym { T 50400 43400 5 10 0 0 180 6 1 device=DUAL_OPAMP T 50400 43600 5 10 0 0 180 6 1 footprint=DIL 14 300 T 50400 43200 5 10 0 0 180 6 1 symversion=0.2 } C 52800 46900 1 0 1 opa.sym { T 52600 49200 5 10 0 0 0 6 1 device=DUAL_OPAMP T 52600 49000 5 10 0 0 0 6 1 footprint=DIL 14 300 T 52600 49400 5 10 0 0 0 6 1 symversion=0.2 } C 52900 49400 1 90 1 resistor.sym { T 52500 49100 5 10 0 0 270 2 1 device=RESISTOR T 53400 48800 5 10 0 1 0 6 1 refdes=R? T 52900 49400 5 10 0 1 270 2 1 footprint=R025DOUBLE T 52900 49000 5 10 1 1 180 6 1 value=100k } N 51100 46300 51100 47300 4 C 52600 49400 1 0 0 3v3.sym C 53900 48400 1 0 1 resistor.sym { T 53600 48800 5 10 0 0 0 6 1 device=RESISTOR T 53300 47900 5 10 0 1 90 2 1 refdes=R? T 53900 48400 5 10 0 1 0 6 1 footprint=R025DOUBLE T 53600 48100 5 10 1 1 0 6 1 value=100k } C 53800 48200 1 0 0 gnd.sym N 51200 45300 51200 44700 4 N 52800 45300 52800 47100 4 N 52800 47500 52800 48500 4 B 51400 46600 2500 1300 3 0 0 0 -1 -1 0 -1 -1 -1 -1 -1 C 51200 44600 1 0 0 output-1.sym { T 51500 44400 5 10 1 1 0 0 1 device=SAW } C 51100 47400 1 180 0 output-1.sym { T 50900 47700 5 10 1 1 180 0 1 device=PULSE } N 51100 47300 51800 47300 4 T 52900 46300 9 10 1 0 0 0 1 PIC COMP1 T 52900 47600 9 10 1 0 0 0 1 RA0/AN0 T 52900 46700 9 10 1 0 0 0 1 RA3/AN3 T 51500 46700 9 10 1 0 0 0 1 RA4/C1OUT T 50200 48300 9 10 1 0 0 0 1 Non-inverting Schmitt Trigger C 52500 45200 1 0 1 resistor.sym { T 52200 45600 5 10 0 0 0 6 1 device=RESISTOR T 51900 44700 5 10 0 1 90 2 1 refdes=R? T 52500 45200 5 10 0 1 0 6 1 footprint=R025DOUBLE T 52200 44900 5 10 1 1 0 6 1 value=100k } N 51200 45300 51600 45300 4 N 52500 45300 52800 45300 4 C 52500 46200 1 0 1 resistor.sym { T 52200 46600 5 10 0 0 0 6 1 device=RESISTOR T 51900 45700 5 10 0 1 90 2 1 refdes=R? T 52500 46200 5 10 0 1 0 6 1 footprint=R025DOUBLE T 52200 45900 5 10 1 1 0 6 1 value=220k } N 52500 46300 52800 46300 4 N 50800 46300 51600 46300 4 N 52800 48500 53000 48500 4 T 52400 45000 9 10 1 0 0 0 1 Pulse is wider due to buffer slew rate. T 53900 40100 9 10 1 0 0 0 1 Tom Schouten T 53900 40400 9 10 1 0 0 0 1 V2 (2014-05)