EEVblog #243 – Vintage Brick Mobile Phone Teardown

What’s inside an almost 20 year old analog mobile phone?

Dave tears down a 1993/1994 vintage Motorola Ultra Sleek 9660 “Dynatac” phone and compares it with a Nokia 3310 from 2000

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  1. You might find the startTAC series was the last of the analog AMPS network phones in 1996. There was a smaller phone than your one from 1989 called the microtac as well

  2. So…no twisting of the case for “sturdy as a brick”?
    Love the retro trip though, thanks!


  3. Dave,

    According to the serial number on that phone it was made in October 1993

  4. That tacking of the coax to the shield might be ground plane.

  5. The TX power required back then was also much greater, because the towers were further apart.

    Those speakers are similar to the ones used in land line phones since forever.


    Phil Hobbs

  6. I was thinking the same thing about the StarTAC, the first flip phone! MUCH smaller than the “brick” phones, still analog

  7. Er, sorry. The MictoTAC was first. My dad’s “work phone” was one of these for many years. I loved the dot-matrix LED display. Sooo futuristic!

  8. Nice teardown.

    In 4 years, the mobile phone downsized by half in both weight and size. The newer battery technology gave it more hours of useage.

    I wonder if the newer digital signal is more efficient than the analog AMPS signal at dumping less microwave energy into the user’s brain.

    It would be nice if you could measure the average electric field strength at, say, 4 inches from the speaker while it is transmitting, and compare it to the digital phone’s average electric field strength at the same distance from the speaker.
    If you still have the old AMPS scanner, you could probably still verify that the old analog phone still puts out RF energy.

    So maybe you could make this measurement even without a working AMPS cellular network. Of course, actually making the measurement would be a lot harder than just talking about it.

  9. Dave, the size of the DynaTAC was governed by the battery, not by the size of the circuitry. The MicroTAC was a direct evolution with a new type of battery and a major shrink of the boards in the late 1990s. The larger DynaTACs were kept on for a number of years as a holdover product for folks who needed something less expensive, if I remember correctly. All info from other engineers when I worked for the Batwing’d co. in the late 90s.

  10. you suppose to loosen the antenna connector before opening. i worked on these phones during 1996 to 2001.

  11. That is one huge phone even for 1994! I had an NEC P4 in 1992 that was almost the same size as the Nokia 6210 that finally replaced it in about 2001 when the Vodafone analogue network was finally switched off in the UK. Coverage in remote areas was better on the analogue NEC using the ETACS network than the Nokia was on GSM.

    Weight = 260g
    Dimensions = 153 x 56 x 30 mm
    Battery life = 1 hour talk time, standby = 24 hours (and double that with the thick battery) Perfectly pocketable, with no lump 🙂
    LCD display as well!

    I always regret throwing away an orignal 1985 Cellnet phone (manufactured by Mobira). It cost about GBP 2500, had a huge lead acid battery in a custom housing that would break your foot if you dropped it. Overall weight heavier than a small child!

  12. I recall tearing apart an even older phone a few years ago; that one had a detachable handset, as the phone itself was absolutely HUGE. Ran off of a large NiCd pack (easily 7x7x15 cm).

    When it comes to analogue phones, there was also the NMT network; I played with some late-model phones which weren’t much larger than the 3310 you showed.

    Oh, and the thing you’re pointing at and calling a microphone is a buzzer (for the ringtone). The red and black wires probably go to the actual microphone, which was already small enough back then.

  13. I’ve got one of those in a box around here somewhere. But it is GSM and even does SMS. You can use it on GSM systems today. It is a Motorola too, certainly newer – maybe 15 years ago – dunno. The battery has gone bad. I would like to find a battery pack that takes AA cells. Ripping apart the original battery pack would ruin it – glued tight.

  14. Dave,

    Have come up against a technical problem with the bench PSU?

    There is little blogs recently or are you milking it 🙂


  15. DynaTac!
    *lol* I misheard that as “DinoTec” when Dave said that 😉

  16. Any guess how many PCB layers that Nokia may have?

  17. My thoughts about size: perhaps they were shooting for a standard landline handset size, since that’s what we were all comfortable with at the time. And I for one, would kill for phones with external antennas again, there’s something to be said for RF performance. But of course my engineering wants != typical customer.

  18. Dave. Thanks to you, whenever I talk about electronics my GF wants me to speak in an Australian accent. Please consider using your fake american accent more often so that I can discuss op-amps over dinner like a normal person.

  19. My fake American accent gets me too many death threats :->

  20. Here’s a scan of my Siemens S3+ (GSM, 1995):
    Unfortunately a friend engaged the device lock. If I only could tap the pins of the 24LC04B EEPROM seen near the Siemens GOLD µC to reset it…

  21. Christian Berger

    Well you can compare it to other analogue phones of the time. For example there was the “Handy” sold by multiple companies That’s where the German word for “cellular phone” came from.
    The German network (C-Netz) was actually fairly advanced, it was close to GSM, but the voice was analogue)
    There were lots of smaller analogue telephones till the German network was turned off around 2000.

    However the typical set was something like this: Those typically gave you features like an answering machine, as well as a socket to connect your fax or modem.

    The AMPS system actually had a nice feature. They wanted to get quick call setup times. Therefore when you made a call, the base station would first let you through, then ask at whatever the AMPS equivalent of the HLR was, if you weren’t a paying subscriber you would get blacklisted, but your first call would still go through.

    What’s more interresting are the _old_ analogue standars. In Germany those started way back in the 1950s. Back then the phones were basically full duplex transcievers with a bit of signalling. Essentially you just had a tone transmitted by the base station if the channel was free. The mobile station could then send its own tone and in that way establish a connection. If you wanted to call out you’d select a channel (some phones would have a scan), take that channel, wait for the operator tell her your phone number and the phone number you wanted to call, and she’d put you through. They later realized the flaw in that procedure and called you back. Calling a subscriber worked by putting a couple of tones on the channel, if you phone found those tones, it would start ‘ringing’ and you could get that channel.

    Later ones (B-Netz) actually had a way for you to dial your number yourself. Early ones apparently were without microcontrollers.
    You had a set of thumb-wheels to set your number. 🙂

  22. Today, I went to the beach with my kids. I found a sea shelland gave it to my 4 year old daughter and said “You can hear the ocean if you put this to your ear.” She placed the shellto her ear and screamed. There was a hermit crab inside andit pinched her ear. She never wants to go back! LoL I knowthis is entirely off topic but I had to tell someone!

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