Using Ic LM338 Make Short Circuit Protection

This is the 1.3 - 32 V / 5A Power Supply w/ Short Circuit Protection . This is a very easy to build power supply that is based on LM338 5A adjustable voltage regulator. I am using the supply for a long time, have no problem yet. Only current adjust is missing but I overcome this situation by using an LCD panel ampermeter.

There is no PCB for the circuit. I took a 3x16 copper plate and strip the unused areas by a knife. If you want you can use analog meters instead of LCD panels.

 Notes

• Use thick wires for connections.
• When connecting the LM338 to the heatsink use thermal paste.
• Use external supplies for LCD panels. They can be 9V batteries. The panels I use draws 1mA current and the batteries last sufficiently long time. If you have small transformers which can supply regulated 9V, you can use them. You need separate transformers for each panel!
• The transformer should be 100 Watt but if you don't need high current you can try transformers that you already have. (I can draw 6A from 100Watt transformer.)
• If you have multi winding transformer you can use the diode connections shown in schematic. Diodes must be 10-15 A.
• Be careful while connecting LM338. Don't put it inverse.
• Output of your transformer mustn't exceed 25V AC.

This circuit operates with high power! Be careful while building and using it!

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Tester for 74xx04 and 74xx14 ICs Circuit Diagram

 The integrated circuits (ICs) 74xx04 and 74xx14 are very frequently used and reused during circuit design. Here xx stands for HC, HCT, AC and LS, etc. Sometimes, the internal inverters of these ICs get damaged. So, it is very important to test these ICs before initiating any experiment and sometimes during the experiments.

Presented here is a simple circuit which can test these ICs statically and dynamically.

Circuit and working
Fig. 1 shows the circuit diagram of a simple tester for 74xx04 and 74xx14 ICs. The circuit is built around hex inverter IC 74HC04 (IC1) and a few other components. You can also test a 74HC14 hex Schmitt trigger with this circuit.

Static testing. The jumpers J1 through J12 are used during static testing of the inverter IC. When J1 through J6 are closed, J7 through J12 should be kept open, and vice versa. When jumpers J1 through J6 are closed, the input of the corresponding inverter is high and the respective output is low. Then, LED1 through LED6 will glow. If jumpers J7 through J12 are closed, the input of the corresponding inverter is low and the respective output is high. Then, LED7 through LED12 will glow. If any one of the LEDs does not glow, it means that the corresponding gate is damaged.

Fig. 1: Circuit diagram of the simple tester for 74xx04 and 74xx14 ICs

Dynamic testing. During dynamic testing, jumpers J1 through J12 should be kept open. When jumpers J13 through J18 are closed, oscillations are generated on the output of each gate. The frequency varies from 0.5Hz to 10Hz. Here, both the LEDs will blink alternately. Their blinking frequency can be changed with VR1 to VR6, if needed.

If a gate’s (say, N2) output LEDs do not glow, it means that the gate’s (N2’s) segment is damaged.

IC 74xx04 may not oscillate during dynamic testing because it does not have specified internal Schmitt triggers. So, only IC 74xx14 can be checked dynamically. If all LEDs blink alternately, it means your 74xx14 is fine.

The circuit works on a 5V power supply but you can use a higher voltage supply, within limits specified in the datasheet.

Construction and testing
An actual-size, single-side PCB for the simple tester using a socket for the 74xx04 and 74xx14 ICs is shown in Fig. 2 and its component layout in Fig. 3. After assembling the circuit on PCB, enclose it in a suitable plastic case.

Fix two 6-pin connectors CON2 and CON3 for six outputs. Also fix 2-pin terminal connector CON1 for power supply. Jumpers J1 through J18 are used for external shorting. You have to use eighteen 2-pin berg strip male connectors on the PCB for shorting the jumpers. Fix presets VR1 through VR6 on the PCB for frequency control.

Fig. 2: An actual-size, single-side PCB for the simple tester for 74xx04 and 74xx14 ICs

 Fig. 3: Component layout for the PCB

If you want to test an IC, insert it in the 14-pin IC socket. Connectors CON2 and CON3 are provided on the PCB for testing the voltages at each individual gate. Before inserting IC in its socket, verify the test point voltages given in the table (only for inverter gate N1 given here). Similarly, you can verify other internal gates at the respective test points shown in the circuit diagram as well as in the PCB.

 Sourced By: EFY Author: Petre Tzv Petrov

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IC 7805 Turn-On VR Circuit Diagram

This is a simple IC 7805 based Turn-On  VR Circuit Diagram. IC 78XX Series includes three terminal positive voltage regulators commonly available in TO 220 package. These are useful in wide range of applications to give precise output voltage. These regulators have internal current limiting, and thermal shutdown circuitry etc.A logic level can control a 7805 regulator with this circuit. Q2 is a series switching transistor controlled by Ql. Ql is turned on by a logic voltage to its base.

IC 7805 Turn-On  VR Circuit Diagram

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Super Linear IC Siren Circuit Diagram

Super Linear IC Siren Circuit Diagram is the best security alarm siren. This is a simple circuit diagram in this circuit uses a low-frequency, op-amp oscillator and a VCO, both configured from a single MC3405 ~dual op amp and dual comparator, are tbe major components in a siren circuit tbat can be made to produce various warbles and wails, or serve as an audio sweep generator. The only otber active components needed are an MPS Al3 small-signal transistor and a 2N6030 power Darling-ton transistor.

Super Linear IC Siren Circuit Diagram

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