As you may have guessed from previous posts I have a thing for phones. Recently someone on IRC going by the name of
As you may have guessed from previous posts I have a thing for phones. Recently someone on IRC going by the name of posted a link to a Polish shop / museum / thing with a bunch of interesting phones on the wall that they stumbled across whilst looking for information on Pin Ball machines. They did some digging and found out the phones were made by Telkom Telos in Poland
After falling in love with the handset hook mechanism I knew I had to have one so I put the feelers out and found a few on Allegro, a Polish online market place. But that only solved half of the problem, how would I get it to the UK? Fortunatly a friend was over there for a month so they very kindly arranged getting it to the UK for around ~£85 in total.
Some people might say I own too many phones. Those people are wrong. I've got a small collection of Gai-Tronics phones and recently got one of the speed dial memory ones for £20. It's missing the handset cradle, so it's not quite fully operational.
Before I got around to testing it I saw a post on a forum stating that the memory speed dial versions of these phones tend to die prematurely. Someone else suggested it might be due to a dead battery.
I hooked it up and whilst inbound calls worked fine, sure enough the speed dial button didn't work. Hmm. Time to take it apart.
I have a bit of a thing for ruggedised telephones like the ones you see on railways and industrial settings. In the UK the main manufacture is Hubbel, formerly Gai Tronics, formely DAC...
Their phones cost a fortune new but occasionally pop up on EBay for reasonable prices, however they're usually in some state of disrepair and spare parts cost a fortune. £200 for a replacement handset for a £600 phone. Yikes! (Incidentally I suspect this is why the end up on EBay, it makes more sense to buy a new one than try to get spares)
For a long time I've wanted to create my own custom internal controller to replace any that are broken, with the added bonus of converting them to SIP. I had some concerns about interfacing the handset / reciever with a soundcard as telephones generally operate at a different impedance to your average speaker and microphone, so I connected one up as a proof of concept.
I chucked a photo up on Twitter and it was suprisingly popular so I thought I'd document the process
New Teams Headset pic.twitter.com/lOA4McTV5f— Matthew Harrold (@MatthewHarrold) July 29, 2021
I've recently been listening to Pirate and "DX" FM Broadcast radio so I purchased a BG7TBL 88-108M FM BPF Band Pass Filter Ebay and stuck it on the NanoVNA to check it out.
It tested out well, with less than 2dB loss in the passband and 30dB rejection below 50MHz and above 145 MHz. Not much else to say about it, I'm just sharing here for posterity.
APC can get in the sea. Every one of their devices uses a random connector with an obscure pinout for the console port. RJ50, RJ11, 2.5mm Stereo Jack, male DB9, to name a few.
I recently aquired an AP9212 in a job lot and wanted put it to use but didn't know the network config so had to console in. Except the DB9 on the front was male, and my el cheapo USB to RS232 adapter was also male. Hmm. Anyway, some googling later I managed to find the correct pinout, which turns out is just a "normal" null modem cable
Unfortunatly when I aquired it the network interface wasn't working ( I suspect auto negotiation had been disabled) so I needed to console into it to get it factory reset and working.
Well, APC are a bunch of plonkers and tend to use odd connectors and pinouts on their console cables so you spend more money to aquire them. Well, I'm too
smart tight for that, so I looked into making my own with bits I had around the house. After a trip to the parts boxes I returned with an old Cisco Console Cable and some RJ12 connectors and just needed to figure out the required pinout.
After a bit of tweaking I mangaged to get something functional made up
I recently aquired an APC 7922 Switched PDU as part of a bulk purchase. Its a chonky box that sits in the rack at a data centre and distributes power to servers, switches and routers etc much like a 16 gang extension lead but it allows you to remotely switch devices on and off, monitor their power usage, and do things like add delays to devices powering up when the power is restored - useful for managinging in-rush current.
Whilst it's a nice bit of kit its not particuarily useful to me, especially give that the sockets are IEC13, so I thought I'd stick it on eBay where it could still get £100+ despite it being relatively long in the tooth.
Before I listed it I thought I'd do some house keeping - Factory reseting it, testing it worked, getting the firmware up-to-date and finally it was just an excuse to play with it as it has been several years since I worked with this kind of gear.
The following blog post should help you get an APC 7922 upgraded to the latest firmware using FTP. Why FTP? I hear you ask. Well, I can't SCP it because it uses some ancient SSH implementation that wont play ball, and I couldn't find anywhere to download the "Firmware Upgrade Utility" - so FTP it is.