martes, 1 de mayo de 2018


This is a “Warnblinkleuchte für Auto+Fussgänger Taschenlampe”: a hazard-warning pocket flashlight for car and pedestrians. It is a Made in Germany personal safety lamp from the early 70s. Its purpose is simple:light on a warning (orange, flashing light) when faced against the beam of a facing car. The user, a walker on a road at night, wears it and it starts blinking as soon as detects the arriving car.

There is a curious set of vintage ads on it, for instance: PopularMechanics (1971), MotorBoating & Sailing (1971) and AmericanMotorcyclist (1971). 

Interestingly, one of the ads described it as “the world’s first fully automatic transistorized flash warning signal”!
There seems to be an active market for it, for instance here, here, here, here.

The lamp works as intended: it can be set on by a separated switch which bypasses the light sensor and the intermittency circuitry, and it also starts blinking when the light intensity increases, with a sensitivity that can be regulated with a wheel.
I have not tested it at night or on a road: it is an incandescent 3V lamp, so really not a powerful safety device – at least not by today’s standards.

The circuit is on a PCB which cannot be easily removed from the lamp, so I can’t show the actual schematics. The parts can, however, be identified:
- A direct switch to turn the light on,
- A variable resistor, on a wheel, with a switch,
- The light sensor,
- Four transistors, and
- Four resistors plus one electrolytic capacitor.

The variable resistor provides up to 5.5 kOhm. Three of the resistors are clear: 270, 39k and 10k, but the fourth has only two bands (2-0), larger than usual, plus an even larger golden band at the other end. The capacitor is labelled “5 MFD – 3V”.
Three of the transistors are marked with OC 305/1. This seems to be (here and here) equivalent to an NTE158 PNP transistor (here and here). It is a Germanium-based device, and there is still a market for it (here and here). The package is in metal, but they seem slenderer than a TO-18. The fourth transistor is even longer and unmarked (I assume it's a transistor because it is three legged...).
The light sensor is a LDR (light dependent resistor). I have measured approx. xx Ohm at 60 lux and above xx Ohm at 400 lux.

As mentioned above it is not possible to see the back of the PCB. A simple possibility with an LDR, a variable resistor and a PNP is:
The blinking may be controlled with an astable circuit with PNPs (here for NPN), like this one (which clearly does not match the list of parts).

(I have not checked, but it seems likely that the frequency of blinking is affected by the light intensity and the position of the regulating wheel - yes, it is: I have checked).

viernes, 27 de abril de 2018

Coffe Machine Philips HD 5670/A

This seems to be a "mildly old" coffee machine: it has been at my family's home for perhaps 20 years, and I could not find anything on it at internet (besides a complain on a second-hand unit).

It is a bulky unit (almost 30*30*15 cm), which does not use capsules (too modern!): it is a conventional, manual espresso machine. It requires that the granulated and toasted coffee is placed on a cup which is then placed against the steam outlet or grouphead. It also has a separated hot steam supply (the steam wand) for heating the milk (or the water).

Main Parts
The machine has mechanical, hydraulic and electrical parts, in three main systems:
- A pump, which receives (sucks) the water from the water tank and pumps it into a boiler.
- A boiler, which creates pressurized hot steam.
- The electrical controls, with sensors and switches on the other parts.

Besides its very simple control, operation-wise is similar to other coffee machine that I described here.

The electrical part is very simple, as indicated in the attached schematics.
The operation is straight: switch S0 starts the machine on/off and the heating resistor (R1), while switch S1 sets the pump in operation (M1), creating the flow of steam. Switch S2 is in parallel to one of the thermal sensors in the boiler (TH4), so it bypasses its function with a kick of additional steam.
The light RD1 (red) is on as soon as the machine is connected (S0), and the light OR1 (orange) is on when the heating resistor is active.

The Pump
The pump is model CS M3637 from Eaton, Mod CP2, with a power of 70 W working at 25-60ºC. It is of the vibrating or solenoid type, described in another post. (Eaton is a giant, and it seems they do not manufacture these pumps anymore; there are a number of internet sites on these pumps and spares: one example here). It is mounted on rubber pads, and it is protected with a thermal fuse (Microtemp 4204A ZKAFZ 98 C; TH2) attached to the body of the pump. (Here on the operation and coding of these thermal fuses, although this one seems to be older).

The Boiler
Made in, in two pieces, bolted (th boiler in aluminium, the grouphead in inox). There is no mark on it. It has a release valve, manually regulated for the steam wand.

The heating resistor (R1) has approx. 43 ohm, which yields a power of some 1,150 W at 220 V (rated 1,260 W).
There are three temperature sensors in contact with the body: two switches from Campini TY60 T180 (TH3 and TH4), and one thermal fuse Microtemp 4300A ZHAHG 152 C (TH1).
(I'm curious about the two thermal switches and the temperature distribution in the boiler, but I have not yet a thermal camera!)
Here on the operation and coding of the thermal fuse, although this one also seems to be older; and here on the specifications of the Campini thermostat switch (“single pole thermostat with snap-action disc”).

The Switches
The three switches are mechanical, of the push type, normally open, with one pole. The manufacturer is ROLD, series CM. S0 and S1 are model E1026 A1 (they retain the closed position when pushed); Switch S2 is model E2015 A1 (does not retain the position when pushed).
ROLD is an Italian manufacturer, a “leader in the manufacture of components for household appliances”. Their webpage does not have catalogues.

sábado, 7 de abril de 2018

Toaster Kenwood TTP102

I found this toaster a couple of weeks ago, with the main cord cut: here is the “disemboweling”!

The Toaster
The manual is here (from ManualsLib).
It is a simple, 2 slice toaster, with "600-800 W", vertical positioning and some controls which I’ll describe later.
It seems to be out of sale in some places (Amazon-UK, Amazon-DE, Kenwood-DE, Kenwood-PAK, Kenwood-ES) but it is available elsewhere (IND, UK, MasterSparesOnline, PAK, ebay-DE).

The Operation
The device is relatively simple, with 5 “controls”:
- the slice lowering lever,
- the variable "browning control",
- the cancel, defrost and reheat buttons (illuminated).

The Inside
The electrical parts are organized in 4 elements:
- the power switch, with a solenoid,
- the variable resistor (“browning control”),
- the 3 heating panels, and
- the control PCB (with the cancel, defrost and reheat buttons and the timers).

The following pictures show the sequence of opening the toaster.

There seems to be a market of spares for this unit, mostly in the UK (PartMaster, 4Kenwood, BuySpares, eSpares).

The Power Switch and Solenoid
Lowering the slices with the main lever closes a switch, that feeds a solenoid. The lever is then attracted to the solenoid and when the power supply to the solenoid is open, a spring in the lever makes it jump-up, with the slices.

The solenoid is labelled “TA8018”. It is fed from the control board, which supplies it with DC current.
The switch is mounted on a board, with no fuse.

The Variable Resistor
It is a linear variable resistor, labelled “B200K” and I have measured from 300 to 200 kohm. One of the bands on the sides of the support is conductive, the other resistive.

The Heating Panels
There are three heating panels, connected in series. One of them is connected with a single wire to the control board.

I have measured about 25 ohm for the ones on the sides, and 30 ohm in the central one. The heating power is therefore 600 W at 220 V (not 800 W).
Based on the length of the wire, the unit resistivity is approx. 150 ohm/m.
The support is a sort of micaceous paper.
The panels are labelled “TA8018M”.

The Control Board
The control board is connected to:
- the power switch for line,
- the end of the wire at the first heating panel for “neutral”,
- the solenoid, and
- the variable resistor (the “browning control”).

The board supports three push buttons with light, but its core is a chip: TN0841B2 A0201D, which I described here.
The board is labelled as “TA8018GS-D-11”, "E123995", "KB-3151" and “2006-7-15 REV:A”, for which I have not found any reference.

The schematics is as follows:
At the connector:
- 1 is for the "ground" at the heater,
- 2 and 4 are for the solenoid, and 
- 3 is for the AC line.

(The pins of the chip are not correctly identified).

sábado, 30 de diciembre de 2017

Coffee Machine Krups Nespresso XN 2001

A Bit of History
Coffee machines have changed deeply with the appearance of the coffee capsules, not only at home.
The history is interesting: apparently, the idea of coffee capsules was developed at Nestlé in the 70's, but it did not pick-up as business. A second trial in the 80's created Nespresso, which signed contracts with appliance manufacturers to design elegant machines, while Nespresso maintained the name and the supply of the capsules. This confluence created a boom in the market etc. Here the story from Nestlé's side.
The man-behind-the-idea seems to be Eric Favre, not mentioned in the previous link. An engineer at Nestlé, he moved away and created his own company, Monodor, also working on the capsule business (later bought by a Brazilian firm). Here his account.
While in Europe and Asia Nespresso is leader, it seems that in the USA Keurig (K-cups) is their equivalent. There seem to be some design differences between the cups, and one important is that while Nespresso's are made with aluminium, K-cups are in plastic, which raises issues for both. Here a short comparison between the two leaders, and here an article on the recycling issues.

Krups XN 2001
I found this machine thrown on the street: it was missing the receptacle for the capsules, the drip grid and the water tank, but I picked it!

The machine is from Krups, model XN 2001:

The model seems to be retired from production (Amazon), although spares are available ( here and here).
I have not found the manuals, but these seem to be close enough: Essenza C91,  Essenza C99 and Essenza C100.

Although I didn't intend to use it as a coffee machine, I tried to dismount it cleanly. The base has the usual message saying that there are no serviceable parts inside etc., and the plastic parts are attached with what initially seemed to me rivets. I was surprised because even at the repair workshops a rivet is hard to remove, but I though that the high pressure inside might require extra safety.

So, I broke the covers...
... Now I have found that they are screws, not rivets, and that they can be hacked (here and here). The special screws can even be bought in Amazon!

Some pictures of the disassembling process and parts:

The final result after removal of all supporting and protecting elements and the pipes:

Main Parts
The machine has mechanical, hydraulic and control systems, in four main parts:
- A pump, which receives the water from the water tank and pumps it into a boiler,
- A boiler, which creates a pressurized flow of hot water and steam,
- The piston which compresses the coffee capsule and allows the water to go through it,
- An electronic motherboard, with sensors and switches on the other parts.

Without the details of the mother board (see below):
Vibrating Pump
The pump is of the vibrating or solenoid type, from Invensys, model CL7.
The operational principle can be seen in this video. The reason why such pump type is selected (which I never had heard of before) is probably the size and the pressure they can deliver, as explained in this other video.
Invensys, an Italian company, used to be part of Schneider Electric, an European giant, and was purchased in 2011 by ARS, a specialist firm.
The model of the machine seems to be out of production. I have not found the datasheet, but these ones from ARS might be similar.
Neither the pressure nor the volume flow is indicated in the label. From ARS' datasheets it seems that this pump can provide 200 ml/min against a back-pressure of 10 bar. It is also self-priming.
Interestingly, it requires 1.5-2 min off for each minute of operation, probably due to overheating. (It is worthy noting that the manuals don't mention this).

A temperature fuse is attached to the body of the pump. It is labelled: "MICROTEMP SVABGB E5A00 Tf 128 C". The specifications of these fuses can be found here. Although the coding seems to be modified, the fuse seems to have a nominal amperage of 20 A, and a functioning temperature of 128 ºC (which I find both surprisingly high: if the body of the motor is at 128 ºC, how hot will it be inside before the fuse works?)

It is an aluminium body with a plastic base, and a series of connectors. The base can be removed (it is screwed) but the chassis is in one piece.
On the chassis it is labelled as EF1308, 230V 1200W. I have not found any other information.

The water inlet is on the top (of the picture), and the outlet at the bottom, in opposed corners of the chassis. Both are in brass-like alloy, 4 mm outer diam.
Close to the inlet and outlet, and at a slight angle, there are the connecting ends of what seems to be the heating resistor (measured approx. 50 ohm, or 4.9 A for the nominal 1200 W mentioned in the chassis and one of the sheaths of the resistor).
The line (brown cable) and neutral (blue cable) are connected (thermally) to the chassis through sheathed thermal fuses similar to the one described above (but here Tf=167ºC). 
The chassis is grounded. This is the only piece of the machine which is grounded, which I find surprising considering that it handles liquids.
Finally, in one corner of the chassis another sensor is fixed, likely to measure temperature (perhaps an NTC thermistor within the body of a bolt).

The water is transported through flexible pipes with quick fittings:

The Piston
The piston mechanically, manually, compresses the coffee capsule and places it into a suitable socket. It also perforates the capsule and allows the hot water/steam pumped through the boiler to lixiviate the coffee and fall into the cup through the beak.
There is no sensor for the correct positioning of the capsule or the closing of the receptacle.

The Motherboard

The motherboard has some separated groups:
- The heater resistor is fed from a triac in TO-220 package attached to a large heat sink. It is labelled as BTB12 600BW from ST. The datasheet is here. The gate of this triac is controlled from a microcontroller PIC16F676 whose datasheet is here.
- The pump is controlled from a small triac BT134W in SOT-223 package. The datasheet is here. Main terminal 2 (4) is directly linked to the pump, while terminal 1 goes to line, with a 220 uF electrolytic capacitor in parallel. The gate goes through SMDs that I cannot completely track (but see below).
- The power line is also protected with a capacitor CV75K10 (varistor, from Keko; datasheet here).
- Two additional film capacitors type PCX2 337 MKII with 470 nF and 220 nF protect the microcontroller (datasheet).
- The two moment touch switches are in separated modules, with rubber cups, and one LED in the selector of the coffee brewing.

I am not sure about several SMDs, and some connections may be missing, but the schematics of the motherboard (seen from behind) is probably something similar to this: