Here is a quick look inside the FE-5060A Rubidium Frequency Standard. Above you can see the entire physics package, with the rubidium lamp housing on the right hand side. The ribbon cable running into the resonator cavity has the power & signal traces for the internal heater, temperaturesensor & Helmholtz coil.
Lamp End
Here is the lamp end of the physics package, with the voltageregulator & RFdriver for the lamp. The FETs soldered to the back of the housing are being used as heaters to maintain a constant temperature on the lamp in operation.
The temperaturesensor can be seen between the two FETs, with a single copper wire running around the housing to connect to it.
Main frequency synth board. This contains the RS-232 interface & the AD9830A from Analog Devices. This IC is a direct digital synthesizer & waveform generator.
This is a late 90’s business timeclock, used for maintaining records of staff working times, by printing the time when used on a sheet of card.
Front Internal
Here is the top cover removed, which is normally locked in place to stop tampering. The unit is programmed with the 3 buttons & the row of DIP switches along the top edge.
Instructions
Closeup of the settings panel, with all the various DIP switch options.
CPU & Display
Cover plate removed from the top, showing the LCD & CPU board, the backup battery normally fits behind this. The CPU is a 4-bit microcontroller from NEC, with built in LCD driver.
PSU & Drivers
Power Supply & prinhead drivers. This board is fitted with several NPN Darlington transistor arrays for driving the dox matrix printhead.
Printhead
Printhead assembly itself. The print ribbon fits over the top of the head & over the pins at the bottom. The drive hammers & solenoids are housed in the circular top of the unit.
Printhead Bottom
Bottom of the print head showing the row of impact pins used to create the printout.
Bottom of the solenoid assembly with the ribbon cable for power. There are 9 solenoids, to operate the 9 pins in the head.
Return Spring
Top layer of the printhead assembly, showing the leaf spring used to hold the hammers in the correct positions.
Hammers
Hammer assembly. The fingers on the ends of the arms push on the pins to strike through the ribbon onto the card.
Solenoids
The ring of solenoids at the centre of the assembly. These are driven with 3A darlington power arrays on the PSU board.
Gearbox Internals
There is only a single drive motor in the entire unit, that both clamps the card for printing & moves the printhead laterally across the card. Through a rack & pinion this also advances the ribbon with each print.
Here is an old chemical dosing system for industrial washing machines. These units are 4-pump models, with dual pumpheads. The motors are reversed to operate alternate pumps in the same head.
Label
From 2006, this is a fairly old unit, and made in the UK.
CPU Board
Main controller PCB, with interface to the power electronics via the ribbon cable, an external serial port for programming to it’s left. Powered by an ST microcontroller. The LCD is below this board.
PCU & Driver PCBs
Main power supply, sense input & motor driver boards. The PSU outputs +5v, +12v & +24v. The inputs on the lower left connect to the washing machine & trigger the pumps via the programming on the CPU. The motors are driven by L6202 H-Bridge drivers from ST.
Motor Assembly
Motor & gearbox assembly on the back of the pumphead. These are 24v DC units with 80RPM gearboxes.
UPDATE:
As it seems to be difficult to find, here is the user manual for this unit:
[download id=”5557″]
After seeing these on eBay for £8.99 I thought it might be a good deal – interfacing with the RasPi’s GPIO & it has built in power supplies.
As a kit, it was very easy to assemble, the PCB quality is high, and is a fairly good design. It worked first time, the regulators hold the rails at the right voltages.
However there are some issues with this board that bug me.
The documentation for the kit is *AWFUL*. No mention of the regulators on the parts list & which goes where – I had to carefully examine the schematics to find out those details.
The 4x 1N1007 diodes required weren’t even included in the kit! Luckily I had some 1N4148 high speed diodes lying around & even though they’re rated for 200mA continuous rather than the specified part’s 1A rating, the lack of heatsinking on the regulators wouldn’t allow use anywhere near 1A, so this isn’t much of a problem.
Component numbering on the silkscreen isn’t consistent – it jumps from R3 straight to R6! These issues could be slightly confusing for the novice builder, and considering the demographic of the RasPi, could be seen as big issues.
On the far left of the board are the 5v & 3.3v regulators, well placed on the edge of the board in case a heatsink may be required in the future. However the LM317 adjustable regulator is stuck right in the middle of the PCB – no chance of being able to fit a heatsink, & the device itself seems incredibly cheap – the heatsink tab on the back of the TO-220 is the thinnest I have ever seen. Not the usual 2-3mm thick copper of the 5v & 3.3v parts – but barely more than a mm thick, so it’s not going to be able to cope with much power dissipation without overheating quickly.
As the adjustable rail can go between ~2.5v – 10v, at the low end of the range the power dissipation is going to shoot through the roof.
The GPIO connector – this could have been done the other way, at the moment the ribbon cable has to be twisted to get both the Pi & the GPIO board the same way up. Just a slight fail there. See the image below
Plugged In
The power rails are not isolated out of the box – there is no connection between the 5v & 3.3v rails & the Pi’s GPIO, but the GND connections are linked together on the board.
Getting the ribbon cable through the hole in the ModMyPi case was a bit of a faff – the connector is too big! I had to squeeze the connector through at a 45° angle. The case is also remarkably tight around the connector once it’s fitted to the board – clearly the designers of the case didn’t test the an IDC connector in the case before making them!
Everything does fit though, after a little modification.
All Cased Up
Here is the unit all built up with the case. The top cover just about fits with the IDC connector on the GPIO header.
More to come once I get some time to do some interfacing!
Here is a label maker, bought on offer at Maplin Electronics. Full Qwerty keyboard with 1 line dot matrix LCD display visible here. Power is 4 AAA cells or a 6v DC Adaptor.
Rear
Rear cover removed. Battery compartment is on the left hand side, space for the tape cartridge on the right. Ribbon cable leading to the thermal print head is on the far right, with rubber tape drive roller.
PCB
PCB under the top cover with the main CPU, a MN101C77CBM from Panasonic. This CPU features 48K Mask ROM & 3K of RAM. Max clock frequency is 20MHz. 32kHz clock crystal visible underneath a Rohm BA6220 Electronic speed controller IC.
This is used to drive the printer motor at a constant accurate speed, to feed the tape past the thermal head. Miniature potentiometer adjusts speed.
Ribbon cable at the bottom of the board connects to the print head, various wiring at the left connects to the battery & DC Jack.
Printer Drive
Printer drive mechanism. Small DC motor drives the pinch roller though a gear train. DC Jack & reverse polarity protection diode is on the right.
This unit uses a centre negative DC jack, which is unusual.
Cartridge
Thermal tape cartridge, black text on white background.
Tip Jar
If you’ve found my content useful, please consider leaving a donation by clicking the Tip Jar below!
All collected funds go towards new content & the costs of keeping the server online.
