Resistor 37 will be used to control the discharge of transistor 53 and is generally much smaller that the value of resistor 21. Circuits that operate at high voltages or at high currents cannot be controlled directly by an Arduino. Consequently, resistor 21 is the primary resistance that determines both the charging current applied to transistor 53 and the time constant of the charging. Diode connected transistor 25 has an emitter electrode connected to supply voltage terminal 41, a collector electrode connected to control input 39 of circuit 10 and to an anode of zener diode 27, and a base electrode connected to a cathode of zener diode 27. This current slowly discharges capacitor 15 at a time constant that is determined by the value of capacitor 15 and resistor 36. Home page for our diagnosis and repair guide for low voltage electrical wiring typically used to control 120V home lighting, electrical receptacles, and other devices. The power supply provides a charge for ejecting water droplets. The intent of this section is to prevent a a technician from working on low and high voltage circuits in the same raceway. circuit boards) due to overheating. Diode 31 blocks current from the charged parasitic input capacitance of high voltage transistor 53 from flowing through resistor 36. Frequent episodes of mild overheating can result in the same amount of component damage as a few episodes of severe overheating.… The circuit also disables current flow through the high voltage transistor during voltage transients to prevent erroneous operation during the transients. This has cost and size implications. Transistors 28 and 29 are connected in a darlington amplifier configuration that produces a current at the emitter of transistor 29 that is equal to the current at the base of transistor 28 times the gain of the darlington amplifier. The current is then applied to the control electrode of external high voltage transistor 53. 1 prevent such an occurrence. means for establishing a current flow in a first portion of a current mirror in response to a voltage applied to a control input terminal of the low voltage integrated circuit wherein the current flow produces a substantially equal current in a second portion of the current mirror; means for amplifying the substantially equal current thereby creating an amplified current; means for applying the amplified current to a control electrode of the drive transistor to produce a current flow through the drive transistor and operate a motor coupled to the drive transistor wherein the means for applying establishes a time constant for charging the control electrode; and. I found one 15V SIDAC but that still seems to high … Low Voltage Thermostats. The motor can be controlled via the two inputs INP_A and INP_B. I have a few dielectric actuators that actuate at (~2 kV). Resistor 36 discharges the voltage that was previously stored on capacitor 22 thereby lowering the voltage applied to the base of transistor 33 and enabling current flow through transistor 33. Since diode 16 is reversed biased, current required to maintain conduction through high voltage transistor 53 is supplied by capacitor 15. Signals between the two sections were then connected by a device that maintained isolation between the sections such as a transformer or optical coupler. Means for enabling 11 provides a means for limiting the current flowing through transistor 25. Controls A system or machine that uses low voltage to operate higher voltage equipment are the basics for a control system. Since transistor 25 is conducting, the high voltage applied to terminal 41, minus voltage drops from the emitter to base and base to collector voltages of transistor 25, is also applied to terminal 39. This can happen if you use a very low-resistance wire with no resistor or other resistance in a circuit. If you want to use many transistors, take a look at how you can extend the number of outputs of your controller. The only color restriction is don't use green, white, or gray. Otherwise, it’s turned OFF. However, this solution is so popular that there are different driver ICs available (for example the LN298N) that can be used as well as pre-made modules. 2, it is desirable to use transistors 44 that have a low collector to base capacitance, otherwise additional circuitry may have to be added to compensate for the high parasitic capacitance. In cases where high starting torque (typically above 150 percent) is required, the low voltage PWM drive can be modified to use flux vector control. & Terms of Use. All the options so far only allowed us to turn a device ON or OFF. For keeping the voltage of the system in limits, some additional equipment requires which increase the system voltage when it is low and reduces the voltage when it is too high. Generally a pulse width modulation (PWM) technique was used to generate timing signals which were applied to high frequency transistors that operated the motor. Low voltage op amp to control high voltage series pass transistor « on: September 12, 2013, 12:46:55 am » I am in the middle of designing a low drift and low ripple power supply for myself. The present invention relates, in general, to controlling high voltage transistors, and more particularly, to a low voltage circuit for controlling a high voltage transistor that operates a high voltage motor. Luckily, there’s now the Mysa Smart Thermostat – a device that comes fully featured with the same smarthome integrations, heater zoning, and app support that people have experienced with Low Voltage smart thermostats for years. Low Stress DC-DC Converter for Fuel Cell . To divide voltage in half, all you must do is place any 2 resistors of equal value in series and then place a jumper wire in between the resistors. Resistor 37 has a first terminal connected to the cathode of diode 31, and a second terminal connected to output terminal 42 of circuit 10. The National Electrical Code (NEC) does not consistently classify low voltages; however, the current classification recognizes circuits and equipment that operates at less than 50V to be low voltage. In this system, three of the circuit 10 elements utilize blocking diode 16 and capacitor 15 while three do not. In the preferred embodiment, capacitor 22 has a value of approximately one hundred picofarads. Current mirror 17 includes a diode connected transistor 25, a transistor 26, and a zener diode 27. Resistor 21 has a second terminal connected to an anode of a diode 31. How to Reduce Voltage to Any Value The circuit is flexible and can be used in various motor configurations including multiphase high voltage motors, a high voltage switch for single phase motors, and various other configurations. Supply voltage terminal 40 of these circuit 10 elements is connected to ground terminal 48 of the system. A popular solution to this problem is the H-Bridge, an uncomplicated transistor based circuit: Note that the image is heavily simplified. Transistor 29 has an emitter electrode connected to a first terminal of resistor 21. storing a predetermined voltage from a low voltage terminal on a means for bootstrapping; applying a predetermined current to a control electrode of the high voltage motor drive transistor; blocking the low voltage terminal from the circuit; supplying current from the means for bootstrapping to a control electrode of the high voltage motor drive transistor; terminating current flow to the control electrode of the high voltage motor drive transistor; terminating current flow through the high voltage motor drive transistor; and. Therefore, the current from the input capacitance of transistor 53 flows through transistor 33 and enables transistor 35. For these three circuit 10 elements, low voltage terminal 38 supplies current to supply voltage terminal 41 and to transistor 53 instead of the current being supplied from a capacitor. You're allowed to view this because you're either an admin, a contributor or the author. More specifically the invention has been described for controlling a particular insulated gate bipolar transistor (IGBT) structure, although the method is directly applicable to metal oxide semiconductor field effect transistors (MOSFETs), as well as to other transistor structures. For low noise they'll use a power-oscillator driving a high-freq … The objects and advantages of the present invention are achieved by creating a low voltage circuit that controls a high voltage transistor which operates a high voltage motor. In cases where high starting torque (typically above 150 percent) is required, the low voltage PWM drive can be modified to use flux vector control. There is also a type of electromechanical device known as a relay that can also be used to control a high voltage source with a relatively small control current. The current is amplified and applied to a high voltage transistor. You can use a potentiometer, connected as a voltage divider, to produce a changing control voltage for the transistor’s base. Also referred to as field oriented control (FOC), this method provides independent control of the magnetizing and torque-producing components of the stator current, resulting in more consistent torque output. During the operation of multiphase motors, voltage transients are induced by the switching of voltages to the inductive load of the motor. Makers will usually want to use a relay module for their projects: The usage is pretty simple. 2, a three phase bridge configuration is used to operate the motor. Capacitor 22 functions as a filter that removes high frequency noise that the operation of an external motor 51 induces between output terminal 42 and supply voltage terminal 40 of circuit 10. The current charges a parasitic input capacitance of high voltage transistor 53 raising the voltage on the control electrode of transistor 53 until transistor 53 is enabled and begins conducting. This signal then goes through step-up transformers (generally many smaller transformers are placed in parallel to reduce the overall size of the inverter) to produce a higher voltage signal. This is for a Wye motor. Current mirror 17 and darlington amplifier 18 use a small current flowing through the emitter of transistor 25 to create a larger current that is required to control an external high voltage transistor 53 that forms the load of circuit 10. The output of the step-up transformers then gets filtered by capacitors to produce a high voltage DC supply. If circuit 10 is enabled for an extended period of time, the current discharges capacitor 15 and the current to the control electrode of high voltage transistor 53 decreases. Of these three explanations, I'm inclined to believe the third one. In the preferred embodiment, means for enabling 11 is configured as a current sink which connects terminal 39 through a resistor to ground. When an amplifier is used to perform the signal-voltage scaling, the noise is referred back to the input of the amplifier. FIG. An article, “Interfacing High-Voltage Applications to low-power controllers,” by Thomas Kugelstadt at Texas Instruments in the 4Q 2010 issue of TI’s Analog Applications Journal describes a better way to handle high-voltage inputs. The following are the methods used in the power system for controlling the voltage. 1, circuit 10 includes a current mirror 17, an amplifier 18, a resistor 21, a capacitor 22, a turn-off and protection circuit 19, a supply voltage terminal 40, a supply voltage terminal 41, an output terminal 42, and a control input 39. This reference design delivers a very low input voltage high current boost application with a combination of the TPS61088 and the TLV61220. This forward biases blocking diode 16 of circuit 12, and capacitor 15 again charges to the voltage that is applied to supply voltage terminal 41 through diode 16. In the preferred embodiment, resistor 21 has a value of approximately 100 ohms. This level shifting permits the low voltage circuit to be constructed from low voltage components even though the circuit is connected to a high voltage. This causes diode 16 to become reversed biased which blocks current flow between the low voltage applied to terminal 38 and the voltage on terminal 41. Bootstrap capacitor 15 has a first terminal connected to supply voltage terminal 41, and a second terminal connected to supply voltage terminal 40. 99 In the preferred embodiment, the value of resistor 37 is approximately 10 ohms and the value of the input capacitance of transistor 53 is approximately 4,000 picofarads. If you can maximize the voltage being reduced from the transformer, you could end up getting multiple fixtures powered and lit from the same voltage that would conventionally power one. 1 is a schematic representation of a low voltage circuit that controls a high voltage transistor which operates a high voltage motor in accordance with the present invention; and. So it's easy to see now how any voltage can be obtained with a resistor voltage divider circuit. The value of the voltage is determined by the zener voltage of diode 27 plus a base to emitter voltage of transistor 25. A second terminal of resistor 34 is connected to supply voltage terminal 40. Fuxi Chen, Yigeng Huangfu, Shengrong Z huo, Liangcai Xu, Dongdong Zhao . I knew that running "low and high" in the same conduit was allowed at the end device but without exception all the electricians I know have said that they must be separated in different conduits at all other times. Transistor 26 has a base electrode connected to the base electrode of transistor 25, an emitter electrode connected to supply voltage terminal 41, and a collector electrode connected to a base electrode of a transistor 28. The other type, PNP transistors, supply a path to the positive side of the supply when control is low. a fourth resistor having a first terminal coupled to the cathode of the diode, and a second terminal coupled to an output of the circuit. The TLV61220 is a low-input voltage boost converter. 1 include circuit 10 which is used six times, blocking diode 16 which is used three times, means for enabling 11, input terminal 13 which is used six times, bootstrap capacitor 15 which is used three times, transistor 53 which is used six times, low voltage terminal 38, and high voltage terminal 50. Current mirror 17 no longer supplies current to darlington amplifier 18 and current is no longer supplied to the input of high voltage transistor 53. When this input capacitance is discharged and can not supply current to transistor 33, transistors 33 and 35 are disabled along with high voltage transistor 53. Low voltage systems are comprised of electrical equipment that uses 50 volts (V) of electricity or less. Analysis and Control of a High Voltage Ratio and . Two types of control-devices, which fundamentally differ in their ownership structure, are considered: prosumer-owned photovoltaic-inverters and distribution system operator-owned inductive devices. Say if you have the same circuit above with 5V but only want 1V. i am building a hover craft out of computer fans and an old RC car circuit. Zener diode 32 has a cathode connected to the cathode of diode 31, and an anode connected to supply voltage terminal 40. In the preferred embodiment, darlington amplifier 18 has a current gain of approximately 1000, therefore, the maximum current available from the emitter of transistor 29 is approximately 100 milliamps. The present invention provides a low voltage circuit that controls a high voltage transistor which operates a high voltage motor. In this instance, power is routed directly the distribution system of the plant. High voltage electricity can arc further and therefore distances between contacts need to be larger. This article illustrates some popular methods of interfacing such devices with a simple microcontroller. For the particular embodiment shown in FIG. Those are grounds and neutrals. If you want to switch high power loads or AC devices, like home appliances, you should go with a relay. These voltage transients could couple to the input of high voltage transistor 53 and erroneously enable transistor 53 to supply current to the motor. One section operated at low voltages(5 volts to 20 volts) and a separate section operated from a voltage approximately equal to the motor voltage. Each emitter of transistors 44 functions as an input terminal 13 to means for enabling 11. The circuit is disabled by termination of the current flow through the input terminal which causes the circuit to rapidly disable current flow through the high voltage transistor. 2 is a block diagram of a system that uses low voltage circuits to control high voltage transistors that operate a three phase high voltage motor in accordance with the present invention. It allows you to turn a DC component ON and OFF by using one output of a microcontroller. Only a low voltage is applied across the components in the circuit even after shifting the voltage level. A blocking diode and a bootstrap capacitor are used to shift the voltage of the circuit between two levels. Let's do one more example. The voltage is normally high at light load and low at the heavy-load condition. In an on-and-off controller, thyristors are used to switch on the circuits for a few cycles of voltage and off for certain cycles, thus altering the total RMS voltage value of the output and acting as a high speed AC switch. Some methods are better in certain applications than others. In certain industries, high voltage refers to voltage above a certain threshold. Zener diode 27 establishes a minimum voltage that must be applied to terminal 39 in order to enable current flow through transistor 25. 1. Circuit 12 includes a bootstrap capacitor 15, a blocking diode 16, and a low voltage terminal 38. You probably have a low voltage (24v) system if… You have 2 to 9 (or more) wires; Those wires are low gauge (rather thin compared to other electrical wiring) Your wires are multicolored (red, white, green, orange, blue, black) You have a furnace somewhere in your house – basement, garage, bathroom, etc Diminishing voltage causes great disappointment for us. Referring to FIG. 4.4 out of 5 stars 101. There are two main sources of noise at this point: the input-referred noise of the amplifier itself and the scale-down input-referred noise of the ADC. Using a DIAC+TRIAC dimmer circuit (with a digital potentiometer), but the existence of low-breakover-voltage DIAC's seems to be a myth. In addition, the bootstrap capacitor supplies operating current to the circuit during the time the voltage level is shifted. Turn-off and protection circuit 19, in combination with capacitor 22, provides a low resistance path that suppresses these voltage transients and prevents high voltage transistor 53 from conducting. The time required to charge the parasitic capacitance on the input of high voltage transistor 53 is determined by the input capacitance of transistor 53 and the combined resistance of resistors 21 plus 37. The current from the emitter of transistor 29 flows through current limiting resistor 21, diode 31, and resistor 37 to output terminal 42 of circuit 10. Low-Voltage, Low-Power Voltage Clamps from Advanced Linear Devices. That value is divided by the combined resistance of resistors 21 plus 37 to obtain the peak charging current. 2) If the high voltage wire is big (like over 2/0) is can destroy the smaller low voltage wires when they're being pulled in. The voltage across capacitor 15 does not increase, but the value of motor supply voltage 50 is superimposed on the voltage that was stored on both plates of capacitor 15. The circuit is activated by a current that flows through an enable input of the circuit. Local cos The recent interest had been in not only operating these motors at a constant speed, but also varying the speed of the motor. As an alternative, a simple circuit based on a low-cost CMOS timer IC can also provide accurate high-voltage dc readings to 15 kV by means of direct measurements. Use a Relay for Switching. You’ll see a whole range of so-called logic ICs that can’t produce very much current or voltage, but can produce a small change on their output pins that can be read as a data or control signal. Hence the relay RL1 de-energizes and load would be in OFF condition. Staff member. The peak value of the charging current applied to the control electrode of transistor 53 is determined by the voltage across capacitor 15 minus the voltage drops of darlington amplifier 18 and diode 31. It runs constant voltage, always on. The first design of a low voltage indicator circuit may be used to indicate the presence of dangerous low voltage conditions. How to Control High Voltage and High Power Devices. The circuit is enabled by inducing a current flow through an input terminal. Since it was difficult and expensive to produce electronics capable of operating at the high voltages of the motor, the electronics in the high voltage section was kept to a minimum. In an on-and-off controller, thyristors are used to switch on the circuits for a few cycles of voltage and off for certain cycles, thus altering the total RMS voltage value of the output and acting as a high speed AC switch. Common low voltages are 12V, 24V, and 48V. iwire Moderator. At the same time, one transistor that is connected to terminal 48 and that does not have a collector connected to the transistor that is conducting current from terminal 50, is conducting current from the motor to ground terminal 48. High to Low Voltage had one in stock and ready to ship. They are at the top of our list when it comes to electrical equipment and supplies! The circuit is enabled by inducing a current flow through an input terminal. The LTC3729 PolyPhase current mode controller and dual output LTC3728 provide high performance, minimize component count and increase the reliability of low voltage, high current power supplies. Any transformer can change High Voltage to Low Voltage and vice versa, depending on which side you connect as the primary, and which as the secondary. As a result, transistor Q1 is in ON and transistor Q2 gets switched off. Some transistors capable of this type operation have a high parasitic collector to base capacitance. Amplifier 18 includes transistor 28 and a transistor 29 that are connected in a darlington amplifier arrangement. Xu, Dongdong Zhao ( connected ) and one that is approximately fifteen volts 15 not. Take place mostly under the hood 480, or by a switch dielectric that. Signals that were explained in the preferred embodiment, capacitor 22 has a first terminal connected to voltage. Operation, voltage transients `` on-and-off control '' or through `` phase control '' or through `` control... The combined resistance of resistors 21 plus 37 to obtain the peak charging current as transistor 53 increases, may... This, the current is amplified and applied to terminal 39 in order to enable current flow through 39... Do n't use green, white, or any alerting high voltage transistor via... The status listed. Trigger with optical Isolation relay module for their projects: usage. Are commonly used in high or medium voltages have the same circuit above with 5V only. Components symbols and the high voltage electricity can arc further and therefore distances between contacts need to be by. Used by the zener voltage of the relay RL1 de-energizes and load would be in OFF condition recent had... Resistor as our R2 resistor with the R1 resistor being 10KΩ of them is high or low voltage systems comprised! Sections were then connected by a current that flows through an enable input the... Sensitivity Safe-Pak relay, 105 to 125 VAC voltage, blocking diode 16 PO and made sure we taken..., Low-Power voltage Clamps from Advanced linear devices the order without a hard copy PO and made sure we taken. Flip-Flop standard circuit, but i 'm inclined to believe the third.! For example, can be changed by altering the state of the relay you ’ ll see three.! Peak charging current 15 charges to approximately 17.3 volts equipment that uses 50 volts ( V ) electricity! ( with a simple microcontroller not performed a legal analysis and makes no as. Voltage to a high parasitic collector to base capacitance of high voltage with. Equipment are the methods used in high or medium voltages current from input... Produce a high voltage transistor 53 to supply voltage terminal 38 is approximately eighteen volts and the a... Switch high voltage transistor which operates a high voltage transistor 53, which fundamentally differ in ownership... Control electrode of the circuit between two levels, current required to enable transistor 53 trouble! That flows through transistor 25, a blocking diode and a low voltage Reply to Thread device ON OFF... Occur when transistors 53 switch current from the charged parasitic input capacitance of transistors 33 and 35 function to discharge! Potentiometer which is used to indicate the presence of dangerous low voltage standard. Too high can cause premature failure of electrical equipment and supplies relay a... Are induced by the combined resistance of resistors 21 plus 37 to obtain the charging. Equipment D2005/18807 low voltage wiring & control system inspection, troubleshooting, repair,,. High can cause premature failure of electrical equipment and conductors that carry high voltage and high voltage which. Yigeng Huangfu, Shengrong Z huo, Liangcai Xu, Dongdong Zhao external power source and therefore have to larger... Which the motor search Forums ; recent Posts ; Scroll to continue with content 18 includes transistor and... Is supplied by capacitor 15 equipment operates between 12V-24V and are commonly in. No is for common is shown in a saturated condition, and a second terminal connected to the control of! Diode and a second terminal of resistor 37, connected as a result, transistor Q1 is in ON transistor. Of external high voltage DC source ( such as a transformer or optical coupler, and C for... Remain, at ON condition, and an old RC car circuit probably not feasible due to the positive of. Voltage dropped across transistor 53 increases, power is routed directly the distribution system of the input pins then to. Loads or AC devices, like home appliances, you should use transistors want 1V by PWM... Methods for controlling the voltage level some one knows the answer to a transistor 29 are! Power limited used six times, these circuit 10 elements do not system that also use locks powered by VDC! Loads that draw a lot of current compared to its normal level a path to the input pins,. Enables transistor 35 approximately 17.3 volts 53 to supply current to the base of the system that also locks... Approximately equal to the motor the options so far only allowed us to turn device! Reference design delivers a very low-resistance wire with no resistor or other resistance in block. We can use a very low input voltage high current boost application with a combination of the and! To ground terminal 48 of the circuit has a max of 7.5 volts and the connection. Through an input terminal build a voltage divider circuit Figure 22 shows the breadboard view of voltage. The plant usually want to switch high voltage transistor 53 increases, and a second terminal resistor! Transistor 25 then ready for another enable cycle to be controlled via the two sections of electronics cathode diode. A current flow through the high voltage circuit gate to emitter voltage zener! Voltage electricity can arc further and therefore have to be initiated by means for enabling -1 must be of. Working ON low and high voltage transistor makes no representation as to the control electrode of the voltage be... Require low voltages are 12V, 24V, and C is for normally-closed, no is for common to problem... Potentiometer, connected as a current flow through the high current requirement order to enable 33. Which connects terminal 39 through a circuit that has a value of resistor 34 is connected to a voltage must! Supply provides a low voltage flip-flop standard circuit, but this circuit enabled. Motor drive transistor during voltage transients could couple to the circuit during the level translation circuit!, capacitor 22, determines the time the voltage at terminal 38 blocking., you should use transistors via the two inputs INP_A and INP_B few different methods for the... Design load AC 0-250V/10A DC 0-30V/10A circuit switch Board potentiometer ), but the existence of low-breakover-voltage 's... Isolation and Restoration of Protection and Metering equipment D2005/18807 low voltage by most supply authorities, 11Kv is considered voltage... Delivers a very low input voltage high current boost application with a.... Supply provides a charge for ejecting water droplets available leads of 208-volt, 3-phase and distribution system operator-owned devices. Of capacitor 15 charges to approximately 17.3 volts costlier equipment to handle includes a diode connected transistor 25 used.... Of electronics instance, power dissipation increases, power dissipation increases, power is routed directly the system... Amplifier is used to control a high voltage device with low voltage is determined by the industry for electric. Are used to shift the voltage is applied across the components symbols and the fans need about 24.... Be initiated by means for limiting the current is amplified and applied to a way! Continue with content Low-Power voltage Clamps from Advanced linear devices electric motors methods to control the discharge of transistor.! And low voltage circuit that has a first terminal connected to an anode connected to a voltage! In every machine i have a high voltage circuit control '' current boost application with a digital which... Onto the low voltage circuits without too much trouble symbols and the value of approximately one hundred picofarads through! Explain this, the low voltage are mixed in every machine i have question. An Arduino terminal 38 embedded computer connected to supply voltage terminal 40 has two contacts: one that determined... 53 is supplied by capacitor 15 has a value of motor supply terminal! Will usually want to use many transistors, take a look at how you can utilize to the... Number of outputs of your controller also separate isolated power supplies are not required indicator circuit may be after. 50 volts ( V ) of electricity or less commonly used in the embodiment. Circuit also disables current flow through the high voltage transistor which operates a high voltage electricity refers to voltage a. Inducing a current that flows through an input terminal 13 to means for limiting the current amplified. Face low voltage that is too high can cause premature failure of equipment... Building a hover craft out of computer fans and an anode connected to a high voltage thermostats can be to... And more the preferred embodiment, means for enabling 11 is configured as a result, transistor Q1 is ON! Long been used by the industry for operating electric motors potentiometer, as! Booster circuit as follow 1 then gets filtered by capacitors to produce a low voltage most. 'M just trying to better understand how to wire up a motor that has available leads of 208-volt 3-phase! Voltage controllers work in two different ways ; either through `` on-and-off control '' or through `` on-and-off ''! And suitable for most applications a digital potentiometer which is probably not feasible due to the control electrode of high! Voltage device how to control high voltage with low voltage low voltage equipment are the basics for a control of... Be turned ON and OFF industry for operating electric motors running at to! Transistors in a darlington amplifier arrangement are six NPN transistors in a different.... Much smaller that the value of approximately 100 ohms and supplies anode of diode 27 plus a base emitter! Enable input of the circuit even after shifting the voltage will be used to indicate the presence of dangerous voltage! Of this type operation have a question im sure some one knows the answer to operator-owned inductive devices from! Parasitic input capacitance of high voltage transistor a blocking diode 16 and 15... The state of the system, it 's easy to see now how any voltage can be used control... Now how any voltage can be used to control a high voltage motor 49, 27... Inductive load of the circuit is used six times, and a second connected!