Order Number DM54LSJ, DM54LSW, DM74LSWM or DM74LSN. See Package Number J20A, M20B, N20A or W20A 2. Download Fairchild Semiconductor DM74LSN pdf datasheet file. DM74LSN Octal D-type Transparent Latches And Edge-triggered Flip-flops DM74LS Details, datasheet, quote on part number: DM74LSN.

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When the operation is complete, the switch is closed for 2us, discharging the capacitor.

The shielding is provided by the partial groundplane on the component side of the board. This is to supplement an incomplete track. This is made up of a network of tracks over the board. These capacitors are identified on the data board and in the schematic as C through C These boards are controlled by one Control Board in the same crate.

If the signal is more positive than this level, the output will switch low datasheeh if more negative, it will switch high. There are nine data boards in the crate supplied, thus allowing up to channels to be digitised.

During operation there is a potential of mV or less between these two lines. This reads data from each board and writes the data to a computer interface along with a count word. It is a modification to a previous design of The digital signal is finally staticized by U7, 74LS The typical current requirements are:. These are wired back to back between the two ground levels.


This is an octal D-type flip flop with tri-state outputs. Following manufacturers’ guidelines, each ACF integrator is decoupled from both rails by 1.

This documentation concerns the 64 channel Digitiser Data Boards designed in BANK – signal common to each of the data boards from the control board – pulses low for a period determined by data transfer rate of control board, and changes at twice the rate of FINGER.

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The signal fed onto the edge connector is passed directly through the high pass filter. Manufacturers of the board were Precision Engineering Products Chesterton Ltd, who will retain the production artwork for a limited time.

The digitiser dm74ls374b board was designed, developed, fabricated and tested by the author. The integration period is determined by the separate control board.

There is a separate regulator for the digital Vcc, U This power rail separation is to reduce power born noise.

The works reference is:. Nearby C, there are two diodes D1, and D2.

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Full circuit details and user instructions for the control board are in a separate document. To describe the operation of the circuit, channel 1 is used as an example.


The sign of the output of the integrator is detected by a comparator, the output of which is written onto one bit of a 64 bit data register comprising a D-type latch.

The schematic circuit was drawn using OrCAD software. The function of this filter is to block DC signals and to control the overall sensitivity of the integrator. This comprises a 2M resistor package RA1A, and 0. The signal is passed through a 0. This would reduce the gain. Secondly, the component pads adjacent to the ACF packages allow for the addition of a capacitor in parallel to the internal pF.

The operation is identical for all 64 channels. Test Switches There are two switches on the board selected by jumpers. This IC is a quad programmable comparator selected for its low and repeatable input offset voltages.

Refer to the complete schematic diagram at the end of this section. They are provided to facilitate board testing. An integration is then performed across a precision pF capacitor for a single sample interval.

All digital grounds are linked to this plane.