Wie man diese netten kleinen LED-Leselampen aufrüstet

Diese kleinen LED-Tischleuchten sind wirklich nett. Schade, dass sie nicht länger durchhalten. Aber dafür kann man selber sorgen – einfach einen zweiten Akku einbauen.

Diese Lampen bekommt man aus zahllosen chinesischen Quellen, einige nur mit warmweißen LED; einige mit einer zweiten LED-Farbe für andere Lichttemperaturen. Sie haben alle einen Berührungsschalter auf der Oberseite, sind alle 40cm hoch, werden alle über USB-C geladen.

Und zumindest alle, die ich aufgemacht habe, haben Platz für einen zweiten Akku!

Viel einfacher wird’s nicht: Akku bestellen, Stecker anlöten, reinsetzen…

Einige haben sogar einen Anschluss für eine zweite Batterie an der Ladeelektronik. Wie die, die ich im Video umgebaut habe. Andere haben das nicht, je nach Grad der Beherztheit lötet man also den zweiten Akku parallel zum ersten oder tauscht den ersten gegen den größeren neuen aus.

Die Lampen verwenden Standard-18650-LiIon-Zellen, mit 3,7V Zellspannung und in der Regel 2400mAh Kapazität. Es gibt aber bezahlbare größere: Ich habe diese Samsung INR18650 mit Lötfahnen genommen (kein Affilliate-Link, gern irgendwo bestellen). Und weil ich demnächst noch meinen neuen Digitakt aufrüsten will, hab ich gleich ein paar mehr besorgt; kosten 7-8 Euro pro Stück.

Battery holder with second battery next to it, connector and cable soldered to it

Also: Batterie auspacken, vorsichtig Kabel und Stecker anlöten – da sind die Lötfahnen echt gut, wenn man die Batterie nicht überhitzen will – erste Batterie abstöpseln, neue anstöpseln, Lampe testen, alten Akku dazustöpseln, wieder zusammenbauen – viel einfacher wird’s nicht.

…und ich hatte ja nicht kapiert, dass man sie auch dimmen kann!

Bisschen peinlich, aber da musste mich erst meine kluge Tochter drauf bringen: Wenn man den Finger auf dem Sensorschalter lässt, wird die Lampe auf- bzw. abgedimmt.

Stereoping Hardware Controller for Crumar Bit

Stephan (aka umusic6) did some nice work:

Thanks to his efforts, there is now a Bit Edition of Stereoping’s Synth Controller, for Crumar Bit-01/One/99 with the Tauntek firmware. You can read up on the firmware, or order it, here.

(No, this is not an affiliate link, I have no share in this. But I think it’s a great project.)

Midifying Jenny, Step 1: Replacing the old keyboard chip with a Teensy

This is the first post in a series of small projects for retrofitting my JEN SX-1000 monosynth with a simple and cheap MIDI interface controller. Read about the basic idea here. Today, I am designing and building the micro-controller brain of the Jenny retrofit – if you are capable of basic soldering, it should not take you more than two hours and a couple of very common electronic parts.

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Jenny getting her very own phaser…

…and my sweet Lord, does it make her shine!

Nothing fancy here. After inserting the booster/overdrive in between VCO and filter section, I took another of those lovely Musikding.de kits for a phaser, built it, drilled some holes into Jenny’s housing and fitted it.

I have been using Jenny as a bass synth recently, and I am quite impressed by the quantities of life and fun this old machine is adding to the mix. She doesn’t do that much in terms of tonal range, but what she does, she does well.

Drilling holes in Jenny’s front

I rediscovered an old trick when drilling metal: use a bit of alcohol, not on the person drilling, but on the surface you want to drill. And don’t go too fast.

V2.0: A Teensy-based MIDI Controller

Building my own wheels for the Launchpad Pro – once again, with style.

Two weeks ago, I started a little sunday afternoon project, sucessfully building my first own MIDI controller – a pitch bend/mod wheel/midi merge device to serve as a companion to my new Launchpad Pro. Using an Arduino, a prototyping board by SparkFun, and community-made code, I succeeded with surprisingly little effort – the most time-consuming part was finding and fixing the errors I had clumsily soldered into my pathetic excuse for a MIDI interface. But it worked!

Launchpad Companion Controller in actionAs they say, the worst thing that can happen is that you succeed. The quick and easy success made me hungry for more – I started a MIDIfication project for my JEN SX-1000 monophonic synth, based on a Teensy, another microcontroller board that can be used within the Arduino development eco-system but is much better suited to MIDI/USB applications.

V2.0: A Teensy-based MIDI controller

This is actually a side project to that. I looked at my self-made controller and noticed that it is usable but not very playable – I wanted real wheels for the Launchpad, not sliders. So I decided to redo a V2.0 of the controller, based on the Teensy.

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MIDIfying Jenny – A Call To Arms

Isn’t it about time my beloved Jenny got her own MIDI interface?

JEN SX-1000 front with ATMEGA chip

To be sure, microcontroller-based interfaces for the JEN SX-1000 do exist. Apart from the commercial CV/Gate solutions by Kenton, there is Neil Johnson’s keyboard interface design. But even if you can get hold of the PCB – a supplier in the JEN SX-1000 group on Facebook had a batch made – the design has an intimidating parts list, and takes some serious time to build.

Is it possible to do it simpler? Emboldened by my success building a small Arduino-based MIDI controller, I decided to start a midification effort that is

  • easy to do (requiring only basic soldering skills, if any)
  • easy to get (by using components that you can buy on Amazon if you have to),
  • easy to develop (using standard solutions from the Arduino community),
  • easy to schedule (because the project is divided up into little steps, each of which is a small afternoon sub-project with instant gratification),
  • easy to participate (by contributing own ideas and code for parts of the project).

I will describe the basic layout of the MIDI upgrade kit project here. Each step, i.e. each sub-project, will then be treated in a new post, depending how fast I (or the community) get them done.

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„We apologize for the inconvenience.“

Ford Prefect and Arthur Dent - still from the BBC series

You may know these two gentlemen. If not, grab your VHS player, rent out the BBC’s „Hitchhiker’s Guide“ series, watch. Hurry!


If you have tried to send a message, or use the shop, you may have noticed that it did not work in the last two days – or, you didn’t notice, and are still waiting for an answer. A conflict between the Contact Form 7 plugin, which I have rediscovered, and the WP Cerber security plugin made some readjustments necessary. It should all be fine again now.

On the plus side, I had the opportunity to overhaul my shop pages, so if you are interested in an update for the Akai AX-80 or Kawai SX-240, it is easier to find and order. Concerning the Matrix-6, there is news: A very old bug in the firmware has finally been found and eliminated; it made it impossible to set negative DETUNE (parameter 12) values. Oddly enough, nobody except Gregor from Stereoping ever seems to have noticed, so there is no harm in continuing to use the firmware V2.14.

There is a new version V2.15 though – Bob fixed the bug – so if you feel that you need negative detune values, you may order that. Or you may take the opportunity to buy one of the V2.14 firmware PROMs extra cheap – while stocks last.

A love letter to Jenny: Tremolo and Key Tracking Mod

This JEN SX-1000 belongs to Stéphane in France, who wrote to tell me of the three mods he did. I have never seen two of them before – a Tremolo control, and variable filter tracking. Which would make Gordon Reid very, very happy.

So here is Stéphane’s letter:

„Hello, here are some modifications for the Jen synthetone SX1000. Nothing is disconnected. Components are added.“

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A new glide pot for Jenny

A bit of TLC for my oldest synthesizer: Jenny is getting a new potentiometer. As the synth’s pots were rather cheap, open types that gather dust, and are 40 years old now, they have become all scratchy and jumpy. As I have mentioned before, I am not the greatest fan of Kontakt spray and similar solvents/cleaners, so I bought replacements. But I never found the time to actually replace them.

JEN SX-1000's

This knob is a good place to start: The „glide“ potentiometer is in charge of portamento, and it is one of the first things that might make Jenny fail (see Neil Johnson’s site). A faulty glide pot means that the synth will only ever play the same note regardless of which key you press. So I did replace that pot, which is pretty straightforward – you’ll find some pictures in this gallery. (It is a 2.2M linear type BTW.)

Overview of potentiometer values

This is an overview of the potentiometer values, some of them are linear, some logarithmic, a few antilog. The most obvious candidates for replacement, apart from the glide pot, would be Frequency (100k) and Resonance (100k) for the filter, and Tune (10k).

Whitening Jenny’s smile: Bleaching old synth keys

Jenny – my old 70s monosynth – is a beauty, and I love her knobby face. Her smile, though, has yellowed over the decades. So to make Jenny even more attractive, I decided to try and bleach the keys with hydrogen peroxide.

TL;DR: Effect has been minimal, so it’s probably not worth it. But it was fun. If you try it, make the Retrobright bleaching gel, don’t use a hydrogen peroxide bath. And have a good UV source.

Old keys with a slightly newer key on top of them

Jenny’s keyboard compared to a key from a mid-80s Roland JX8P synth

In School, I used to hate chemistry. Did I mention that I used to hate chemistry? Okay, I did (when successfully reviving Jenny’s keyboard contact springs by cooking them)

So here’s what I did.

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