Circuit selection

Methanol oxidation on Pt has been investigated at temperatures 350° to 650°C, CH3OH partial pressures, pM, between 5-10"2 and 1 kPa and oxygen partial pressures, po2, between 1 and 20 kPa.50 Formaldehyde and C02 were the only products detected in measurable concentrations. The open-circuit selectivity to H2CO is of the order of 0.5 and is practically unaffected by gas residence time over the above conditions for methanol conversions below 30%. Consequently the reactions of H2CO and C02 formation can be considered kinetically as two parallel reactions. 

Discrimination in radiation detection circuits refers to the process of distinguishing between different types of radiation on the basis of pulse height. A discriminator circuit selects the minimum or maximum pulse height that is to be counted. 

A discriminator circuit selects the minimum pulse height. When the input pulse exceeds the discriminator preset level, the discriminator generates an output pulse. The discriminator input is normally an amplified and shaped detector signal. This signal is an analog signal because the amplitude is proportional to the energy of the incident particle. 

To simulate circuits, select ophonAlWlog Of Mixed A/D and click the OK button ... 

Before we continue, we would like to zoom in on the circuit and make it as large as possible while still displaying the entire circuit. Select View, Zoom, and then Area from the menus. The mouse pointer will be replaced by a magnifying glass ... 

When you are finished with your circuit, select File and then Save from the Capture menus. This will save the changes to this page only ... 

To simulate the circuit, select PSpice and then Run from the Capture menus ... 

We are now ready to simulate the circuit. Select PSpice from the menu bar and then select Run. Capture will first create an updated netlist and then run PSpice. When the simulation is complete, the Probe window will display an empty plot ... 

We must now set up the Parametric Sweep. If you are continuing from the previous example, you will already have created a simulation profile for the DC Sweep. To open the profile, select PSpice and then Edit Simulation Profile from the menus. If you started this example as a new circuit, select PSpice and then New Simulation Profile, specify a name for the new profile, and then click the Create button. Set up a DC Sweep as shown below. Using either procedure, you should have the screen below ... 

Note that the Sweep Variable is a Voltage source, and that there is a checkmark in the squares to enable both the Secondary and Primary sweeps. The Secondary Sweep uses the Value list, which sets VCE to 2, 5, 10, and 15 volts. Click the OK button to return to the schematic. Simulate the circuit (select PSpice and then Run or press the F11 key) and then view the results with Probe. Plot Hfe versus p Use the same procedure to generate the plot that we used on pages 248-249. Four curves will be displayed ... 

Run the circuit Select PSpice and then Run from the Capture menu bar. When Probe runs, the traces Vin and Vo will be displayed. Note that the time axis only displays times from 490 ms to 500 ms. (This was specified in the Time Domain (Transient) setup dialog box when we set the Run to time to 500 ms and the Start saving data after to 490 ms.)... 

We are now ready to create the subcircuit netlist for this circuit. Select File and then Save to save the circuit, and then select File and then Close to close the window. You should return to the project tree for this circuit. Expand all the branches of the tree ... 

No more errors will be indicated when we create a netlist. However, there are still two errors in the drawing. The first is that the circuit is not grounded. The entire circuit is floating. This error would have been caught when we ran the simulation. You must add a part called 0 to your circuit. Select Place and then Power from the Capture menus to place the ground. 

If a particular type or model is chosen from a manufacturer it can be seen that this low horizontal part may be similar or the same for aU ratings of circuit breakers within the range. Supposing a 2 1 or 3 1 ratio of upstream rating to downstream rating is chosen for a particular circuit. Selective tripping of the downstream unit can only be relied upon for fault currents beyond the magnetic vertical part of the curve for the downstream unit, but less than the vertical part of the upstream unit. For faults beyond the vertical part of the upstream unit there will be a race between both units and the upstream unit may trip before the downstream unit. This is not a satisfactory... 

The circuit design is formulated. Appropriate circuit selection is conducted depending on total conditions such as allowed space, sizes of components, operating temperature, possible assembling process, required reliability, and so on. 

Select a voltage range that provides a midscale reading. When testing a 5-V circuit, select the 10-V scale. If circuit voltage is unknown, select the highest scale and work downward. 

Select a resistance range that will provide a midscale reading. If you are using an 11-kfl circuit, select the 20-kfl scale. 

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