Mains adapter for Philips 3302a cassette recorder(1973) - UK Vintage Radio Repair and Restoration Discussion Forum

Robbie99 · 15th Dec 2016, 3:04 pm

Hi All,

Having replaced the melted drive bands on my otherwise new looking 1973 Philips cassette recorder, (a nostalgia buy because I used to use one to record John Peel shows in the seventies), I now want to make up a mains adapter to power it. Don't want to spend much on this in approach to Xmas, and although I have almost no electronics knowledge I can solder.

I know the six pin DIN should be positive wire to pin 1 and negative to pin 3, and I've got the circuit diagram of the mains socket. My problem is what mains adapter to use with it. I know the machine is designed to run with 7.5v power supply but I've read on the Peter Vis website that it is wise not to wack too much voltage into an old machine.

I do have a spare 6v adapter I could use. I'm assuming as I have a later model this voltage won't affect the playing speed. Unfortunately it is rated as outputting 1.5A which is a lot higher than Peter's suggestion of 300mA or thereabouts. If this adapter is no good, (and feel free to explain why - I'm keen to learn!), can anyone recommend a reliable budget adapter and supplier(s)? Thanks in advance.

threeseven · 15th Dec 2016, 5:08 pm

Just a note on supply current first. Any given device will only take the current it needs, so a power supply that can provide more than the device needs won't force more current into it, assuming the voltage is correct.
Philips did make a multiple voltage mains adaptor that was switchable between 6, 7.5 and 9 volts. It was supplied with a jack to din adaptor for use with many Philips portable devices.
It's designation was N6502, they can be found on ebay but quite rarely.

TonyDuell · 15th Dec 2016, 5:25 pm

There was a plug adapter -- I have no idea if it was a Philips product or not -- which took one of those coaxial power plugs and fitted into a 5 pin type B DIN socket. I have one, it came with a Philips tape recorder (actually an EL3586) I bought second-hand. Yes, I do still want it.

But the connector is not really a problem given that 5 pin type B (240 degree) DIN plugs are not hard to get.

I would not give it more than 7.5V. I don't know if the original mains adapter was voltage-regulated or not (some Philips ones certainly were), but if you are making/buying a replacement, rather than trying to copy the original, there is no good reason now not to fit a voltage regulator. An LM317 and a couple of resistors would do it. With a linear regulator like the LM317 you have to provide it with rather more voltage on the input (say around 12V here) but it doesn't matter within reason what that input voltage is (that's the point of the voltage regulator). The input current will be essentially the same as the output current.

I can't recomend a supply, this the sort of thing I would build from components if I wanted one. So I can't say if this will work, but Maplin N47ED claims to have a 7.5V setting. And at 27W it would easly handle the current of the EL3302. It's not cheap, though. Actually, Maplin L06BR would do, I think and is a bit cheaper. You'd have to make up an adapter lead to the 5 pin DIN socket with any PSU you could buy now.

There would be no danger in using your 6V adapter. As others have said, the machine will draw the current it needs, you will not force 1.5A through it. It may work. It may not give good performance. But it will do no permanent damage.

threeseven · 15th Dec 2016, 5:34 pm

The N6502 was regulated, quite a nice unit actually. I have 2 which still work perfectly and in use regularly.

AC/HL · 15th Dec 2016, 5:57 pm

Circuit here.

threeseven · 15th Dec 2016, 8:04 pm

Thanks for that, I was going to download it but I couldn't remember my password for the Radio Museum site!

GeoffK · 15th Dec 2016, 8:14 pm

This is a simple series supply that could be made on a piece of Vero board and put in a plastic box, the circuit can be modified to make the output voltage adjustable, it doesn't have any short circuit protection but this could be added with a sense resistor and an extra transistor. The recorder would still work with a simple unregulated diode bridge and 1000uF smoothing capacitor. The recorder can have the full 7.5 volts applied as it was designed to operate at this voltage.

TonyDuell · 15th Dec 2016, 8:46 pm

Unless you want to be historically accurate (which would be entirely reasonable), I would not try to copy the Philips power supply. It uses germanium transistors which are getting hard to find and expensive. They may also fail due to old age (search the forum for 'tin whiskers').

You should decide whether you want to buy or build. If you want to buy you will probably end up with what is called a 'switch mode power supply' I think that will be OK for a tape recorder. You would then have to make the adapter lead to link it to the 5 pin DIN socket. All switch mode power supplies are voltage-regulated by the way.

If you are going to build it, you would build a so-called linear supply with a mains transformer, rectifier, smoothing capacitor and regulator circuit. You then need to decide whether to make the regulator out of discrete transistors (as shown in some of the diagrams here) or use a regulator IC. I suggested the LM317 earlier. This device has 3 connections, it looks like a power transistor, and you fix it to a heatsink. You have to wire it up to 2 resistors as shown on the datasheet (which I am sure you can download), the data sheet will tell you how the output voltage is controlled by the resistors.

It's up to you. Make a choice and somebody here will help you with it.

AC/HL · 15th Dec 2016, 8:49 pm

Quote:

Originally Posted by threeseven

Thanks for that, I was going to download it but I couldn't remember my password for the Radio Museum site!

I found it on Google Images amongst all the other illustrations.

mitajohn · 15th Dec 2016, 10:06 pm

You need something like this one: http://www.ebay.co.uk/itm/H-AC-DC-Ad...item41b702f869 and you have to change the plug as the one attached.

Nicklyons2 · 16th Dec 2016, 12:34 am

I think I've got a legit Philips branded power supply; I can't remember whether it's 6 or 7 volts but I can check if you wish. It's 'open ended' at the moment but if you wish I think I can find a DIN plug to put on if it's of any interest.

emeritus · 16th Dec 2016, 1:08 am

During the oil crisis, 3 day week, frequent power cuts, days of the 1970's I used to run my EL3302 from a 6V motor cycle battery with no problems. I had recalled from when we helped a friend fit one to his car in the late 1960's, that the Philips N6705 car mounting unit for it (the one with the caddy that the recorder slots into, allowing both playback and recording) was suitable for both 6V and 12V systems, which is confirmed by the Radiomuseum entry here:

http://www.radiomuseum.org/r/philips...heit_6705.html

Philips also did a car lead (EL2233) for 12V electrics that AFAIR was simply a ventilated metal box containing a watty resistor to drop the excess 6V or so, and a lead with a plug for the recorder. For cars with 6V electrics (such as older VW Beetles), you could just connect directly to the car battery. The EL33xx series draw an approximately constant current of about 90- 100mA (the current drawn by the motor is much greater than the current drawn by the electronics) so a simple series resistor dropper is all that was needed. I made up my own, having discovered by experiment that, contrary to what I had expected, the current did not rise when the end of the tape was reached so that the capstan was bearing on stationary tape and a stationary rubber pinch roller. My plan of detecting the higher current to make an automatic end-of-tape switch-off circuit therefore came to nought. AFAIR, the speed only started to drop when the battery voltage had fallen to about 1V per cell. Thus the effective operating range was around 5.0V to 7.5V, making precise voltage regulation a bit of an overkill.

julie_m · 16th Dec 2016, 1:58 am

I used to run my old EL3302 from a modified (output connector changed to 6-pin DIN) universal unregulated power supply without problems, and also successfully used a 6V spring-terminal lantern battery wired to the DC input.

mitajohn · 16th Dec 2016, 11:03 am

It is very easy to assemble the plug, follow the pic.

Robbie99 · 21st Dec 2016, 12:04 pm

Apologies for late reply I've not had time to check back into the forum for boring work and Christmas panic reasons. Wow, what fantastic response. Really appreciate how helpful, detailed and generous your replies were.

I have decided to use my 6 volt supply with my 6 pin DIN plug. I have now learnt from you that a) the device draws the current it needs and b) that it has a flexible operating voltage range. So thanks again to threeseven, TonyDuell, Hetrodyne, mitajohn, NickyLyons2, emeritus, AC/HL and julie_m . Fingers crossed the machine works when it gets some power!

15th Dec 2016, 3:04 pm	#1
Robbie99 Retired Dormant Member Join Date: Jun 2008 Location: Telford, Shropshire, UK. Posts: 9	Mains adapter for Philips 3302a cassette recorder(1973) Hi All, Having replaced the melted drive bands on my otherwise new looking 1973 Philips cassette recorder, (a nostalgia buy because I used to use one to record John Peel shows in the seventies), I now want to make up a mains adapter to power it. Don't want to spend much on this in approach to Xmas, and although I have almost no electronics knowledge I can solder. I know the six pin DIN should be positive wire to pin 1 and negative to pin 3, and I've got the circuit diagram of the mains socket. My problem is what mains adapter to use with it. I know the machine is designed to run with 7.5v power supply but I've read on the Peter Vis website that it is wise not to wack too much voltage into an old machine. I do have a spare 6v adapter I could use. I'm assuming as I have a later model this voltage won't affect the playing speed. Unfortunately it is rated as outputting 1.5A which is a lot higher than Peter's suggestion of 300mA or thereabouts. If this adapter is no good, (and feel free to explain why - I'm keen to learn!), can anyone recommend a reliable budget adapter and supplier(s)? Thanks in advance.

15th Dec 2016, 5:08 pm	#2
threeseven Octode Join Date: May 2010 Location: Worcestershire, UK. Posts: 1,880	Re: Mains adapter for Philips 3302a cassette recorder(1973) Just a note on supply current first. Any given device will only take the current it needs, so a power supply that can provide more than the device needs won't force more current into it, assuming the voltage is correct. Philips did make a multiple voltage mains adaptor that was switchable between 6, 7.5 and 9 volts. It was supplied with a jack to din adaptor for use with many Philips portable devices. It's designation was N6502, they can be found on ebay but quite rarely. __________________ BVWS member

15th Dec 2016, 5:25 pm	#3
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,222	Re: Mains adapter for Philips 3302a cassette recorder(1973) There was a plug adapter -- I have no idea if it was a Philips product or not -- which took one of those coaxial power plugs and fitted into a 5 pin type B DIN socket. I have one, it came with a Philips tape recorder (actually an EL3586) I bought second-hand. Yes, I do still want it. But the connector is not really a problem given that 5 pin type B (240 degree) DIN plugs are not hard to get. I would not give it more than 7.5V. I don't know if the original mains adapter was voltage-regulated or not (some Philips ones certainly were), but if you are making/buying a replacement, rather than trying to copy the original, there is no good reason now not to fit a voltage regulator. An LM317 and a couple of resistors would do it. With a linear regulator like the LM317 you have to provide it with rather more voltage on the input (say around 12V here) but it doesn't matter within reason what that input voltage is (that's the point of the voltage regulator). The input current will be essentially the same as the output current. I can't recomend a supply, this the sort of thing I would build from components if I wanted one. So I can't say if this will work, but Maplin N47ED claims to have a 7.5V setting. And at 27W it would easly handle the current of the EL3302. It's not cheap, though. Actually, Maplin L06BR would do, I think and is a bit cheaper. You'd have to make up an adapter lead to the 5 pin DIN socket with any PSU you could buy now. There would be no danger in using your 6V adapter. As others have said, the machine will draw the current it needs, you will not force 1.5A through it. It may work. It may not give good performance. But it will do no permanent damage. Last edited by TonyDuell; 15th Dec 2016 at 5:34 pm. Reason: Found another Maplin supply that might work

15th Dec 2016, 5:34 pm	#4
threeseven Octode Join Date: May 2010 Location: Worcestershire, UK. Posts: 1,880	Re: Mains adapter for Philips 3302a cassette recorder(1973) The N6502 was regulated, quite a nice unit actually. I have 2 which still work perfectly and in use regularly. __________________ BVWS member

15th Dec 2016, 5:57 pm	#5
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Mains adapter for Philips 3302a cassette recorder(1973) Circuit here. Attached Thumbnails

15th Dec 2016, 8:04 pm	#6
threeseven Octode Join Date: May 2010 Location: Worcestershire, UK. Posts: 1,880	Re: Mains adapter for Philips 3302a cassette recorder(1973) Thanks for that, I was going to download it but I couldn't remember my password for the Radio Museum site! __________________ BVWS member

15th Dec 2016, 8:14 pm	#7
GeoffK Heptode Join Date: Mar 2016 Location: Essex, UK. Posts: 602	Re: Mains adapter for Philips 3302a cassette recorder(1973) This is a simple series supply that could be made on a piece of Vero board and put in a plastic box, the circuit can be modified to make the output voltage adjustable, it doesn't have any short circuit protection but this could be added with a sense resistor and an extra transistor. The recorder would still work with a simple unregulated diode bridge and 1000uF smoothing capacitor. The recorder can have the full 7.5 volts applied as it was designed to operate at this voltage. Attached Thumbnails Last edited by GeoffK; 15th Dec 2016 at 8:20 pm.

15th Dec 2016, 8:46 pm	#8
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,222	Re: Mains adapter for Philips 3302a cassette recorder(1973) Unless you want to be historically accurate (which would be entirely reasonable), I would not try to copy the Philips power supply. It uses germanium transistors which are getting hard to find and expensive. They may also fail due to old age (search the forum for 'tin whiskers'). You should decide whether you want to buy or build. If you want to buy you will probably end up with what is called a 'switch mode power supply' I think that will be OK for a tape recorder. You would then have to make the adapter lead to link it to the 5 pin DIN socket. All switch mode power supplies are voltage-regulated by the way. If you are going to build it, you would build a so-called linear supply with a mains transformer, rectifier, smoothing capacitor and regulator circuit. You then need to decide whether to make the regulator out of discrete transistors (as shown in some of the diagrams here) or use a regulator IC. I suggested the LM317 earlier. This device has 3 connections, it looks like a power transistor, and you fix it to a heatsink. You have to wire it up to 2 resistors as shown on the datasheet (which I am sure you can download), the data sheet will tell you how the output voltage is controlled by the resistors. It's up to you. Make a choice and somebody here will help you with it.

15th Dec 2016, 10:06 pm	#10
mitajohn Pentode Join Date: Sep 2005 Location: Athens, Greece Posts: 197	Re: Mains adapter for Philips 3302a cassette recorder(1973) You need something like this one: http://www.ebay.co.uk/itm/H-AC-DC-Ad...item41b702f869 and you have to change the plug as the one attached. Attached Thumbnails __________________ Regards, John Last edited by mitajohn; 15th Dec 2016 at 10:34 pm.

16th Dec 2016, 12:34 am	#11
Nicklyons2 Octode Join Date: Jan 2013 Location: Barnsley, South Yorkshire, UK. Posts: 1,517	Re: Mains adapter for Philips 3302a cassette recorder(1973) I think I've got a legit Philips branded power supply; I can't remember whether it's 6 or 7 volts but I can check if you wish. It's 'open ended' at the moment but if you wish I think I can find a DIN plug to put on if it's of any interest.

16th Dec 2016, 1:08 am	#12
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,349	Re: Mains adapter for Philips 3302a cassette recorder(1973) During the oil crisis, 3 day week, frequent power cuts, days of the 1970's I used to run my EL3302 from a 6V motor cycle battery with no problems. I had recalled from when we helped a friend fit one to his car in the late 1960's, that the Philips N6705 car mounting unit for it (the one with the caddy that the recorder slots into, allowing both playback and recording) was suitable for both 6V and 12V systems, which is confirmed by the Radiomuseum entry here: http://www.radiomuseum.org/r/philips...heit_6705.html Philips also did a car lead (EL2233) for 12V electrics that AFAIR was simply a ventilated metal box containing a watty resistor to drop the excess 6V or so, and a lead with a plug for the recorder. For cars with 6V electrics (such as older VW Beetles), you could just connect directly to the car battery. The EL33xx series draw an approximately constant current of about 90- 100mA (the current drawn by the motor is much greater than the current drawn by the electronics) so a simple series resistor dropper is all that was needed. I made up my own, having discovered by experiment that, contrary to what I had expected, the current did not rise when the end of the tape was reached so that the capstan was bearing on stationary tape and a stationary rubber pinch roller. My plan of detecting the higher current to make an automatic end-of-tape switch-off circuit therefore came to nought. AFAIR, the speed only started to drop when the battery voltage had fallen to about 1V per cell. Thus the effective operating range was around 5.0V to 7.5V, making precise voltage regulation a bit of an overkill. Last edited by emeritus; 16th Dec 2016 at 1:17 am.

16th Dec 2016, 1:58 am	#13
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Mains adapter for Philips 3302a cassette recorder(1973) I used to run my old EL3302 from a modified (output connector changed to 6-pin DIN) universal unregulated power supply without problems, and also successfully used a 6V spring-terminal lantern battery wired to the DC input. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

16th Dec 2016, 11:03 am	#14
mitajohn Pentode Join Date: Sep 2005 Location: Athens, Greece Posts: 197	Re: Mains adapter for Philips 3302a cassette recorder(1973) It is very easy to assemble the plug, follow the pic. Attached Thumbnails __________________ Regards, John

21st Dec 2016, 12:04 pm	#15
Robbie99 Retired Dormant Member Join Date: Jun 2008 Location: Telford, Shropshire, UK. Posts: 9	Re: Mains adapter for Philips 3302a cassette recorder(1973) Apologies for late reply I've not had time to check back into the forum for boring work and Christmas panic reasons. Wow, what fantastic response. Really appreciate how helpful, detailed and generous your replies were. I have decided to use my 6 volt supply with my 6 pin DIN plug. I have now learnt from you that a) the device draws the current it needs and b) that it has a flexible operating voltage range. So thanks again to threeseven, TonyDuell, Hetrodyne, mitajohn, NickyLyons2, emeritus, AC/HL and julie_m . Fingers crossed the machine works when it gets some power!