You can use that miniature transformer in conjunction with a switch and wire it to the volume pot, using the switch to disconnect the radio signal, and add a 3.5 mm jack. On that 3.5 mm jack you could add a wireless Bluetooth dongle as another solution. Fantastic schematic and adaptation of your creation.
@@electronicsoldandnewI just want to tell you that I really enjoy your channel and your presentation. In the States I don't get a lot of these types of radios to work on so you are and invaluable source of experience and information. Thank you
Hi Manuel. Will you be posting the board that uses the magic eye tube as a turn on/off circuit for the module soon. I would like to order them together in one shipment. Thanks for this useful video as my Zenith has a hot chassis.
Nice addition to your Bluetooth lineup Manue, The only trouble is Bluetooth is you can't transmit simultaneously to one's whole radio collection. Coming up with a legal AM transmitter with good audio would be nice for the collector, but offers some serious problems.
Can't vouch for this but there is a seller on ebay (orient100) creating Bluetooth to AM radios supposedly not exceeding 50mW (below the unlicensed limit in most countries). They can trim the frequency to suit. Not cheap, but may be a solution.
would it be correct to say using a mains transformer, the dc to dc convertor is no longer needed because you already have isolation /no ground loop (hum) or are you still needing to isolate digital earth from analog earth to prevent digital noise breakthrough?
It is probably not needed with a transformer for that exact reason, but I haven’t experimented with it as yet. Just wanted to see what would be needed to make the same circuit work on a hot chassis.
Greetings From Germany... A question concerning identifying the chassis ground transformer of the radio's schematic and then comparing it to a similar model that has an isolated ground. Is it possible to make a supplementary video or Part 2 just to show us viewers exactly what to look for on the schematic for a positive identification of chassis ground.
You can easily see it from the schematic. One side of the mains is shown as grounded. You can also just test with a multimeter as I did at the start of the video.
@@electronicsoldandnew I think to remember that you forgot in the schematic to show that one side of the 6.3V filament winding of the transformer is connected to ground. You told it, but it is not drawn. Maybe that is the confusion here ?
When you are stil afraid that the audio ground gets on the live mains, you can put in the soldered audio ground a large capacitor, but it would be a 400V 8µ or so. I don't like the sound of 230V getting in your BT board, it is original not designed for that.
The cap would indeed make it safer, but the mains getting to the board is t a problem as long as it doesn’t get anywhere near anything at a different potential. Effectively all you’re doing is elevating the “ground” reference, which isn’t normally a problem.
There seems to be something wrong with the phono input. Normaly the input is not connected directly to chassis but there is always a block capacity of 5nF to chassis ground. No one would ever sell a construction where you can die by touching the phono inputs.
Why don't you design a circuit so you can't plug it in wrong? Have the circuit flip the hot and neutral the correct way or not allow the radio to have power to the chassis.
I am amazed that the EU never passed a law requiring all member states to standardise on the three-pin mains plug we enjoy here in the UK. 🤣🤣🤣 Yes, that was really realy naughty of me but I hope you get my drift. Here in the UK we're not that clever either with our reversible bayonet mains light sockets. I'd outlaw those as well as it's possible to buy B22 socket extension plugs. ⚡ 👿
I agree with you completely 😊 it would be so easy as some of these plugs have a hole on one end which would only require the sockets to have a protruding pin, but I guess they’re being stubborn in this issue.
@@electronicsoldandnew France and other countries plug have 3 pins, but there is no defined neutral wire position, only the ground/protective one. And you can still use 2 wires plug which you can connect both ways. 3 pin with defined ground is only required for devices with metal cover. Btw british plug is too big. Btw Im dissapointed by the design of this little Grundig radio, that there is phono input directly connected to chassis. Standard way for hot chassis radio was to use audio isolation transformer for phono input. Antenna was always protected by small value/high voltage caps (now we call them Y2 caps).
Yes, it’s a pity the plug issue hasn’t been standardised and regulated all over Europe. In Portugal we have no protection as regards mains polarity. The Grundig was a surprise indeed. Initially I didn’t realise it was an auto transformer, and the worst part was the phono ground to chassis connection. I wonder how many people got shocked over the years … totally needless. A proper transformer would have cost very little more than this one, and all the danger removed from the set.
@@electronicsoldandnew There were planty of hot chassis sets in 40s-50s. Copper was expensive, so transformers were expensive too during war and postwar years. But I never saw set where you can touch hot chassis without opening back cover. It looks like error. There is no way how to standardize plugs across Europe - it would be too expensive, you would have to rebuild all electric installation. We in Czech republic also dont have polarized plugs, we use french standard designed in 1920s. German standard doesnt have it too, both wires should be considered as possibly hot.
Why don't you design a circuit so you can't plug it in wrong? Have the circuit flip the hot and neutral the correct way or not allow the radio to have power to the chassis.
Well done my friend! 👍
Thank you
You can use that miniature transformer in conjunction with a switch and wire it to the volume pot, using the switch to disconnect the radio signal, and add a 3.5 mm jack. On that 3.5 mm jack you could add a wireless Bluetooth dongle as another solution. Fantastic schematic and adaptation of your creation.
👍
@@electronicsoldandnewI just want to tell you that I really enjoy your channel and your presentation. In the States I don't get a lot of these types of radios to work on so you are and invaluable source of experience and information. Thank you
My pleasure
Brilliant!
Thanks for sharing.
Pleasure
It would probably be a good idea to use a fuse for the transformer primary and secondary winding.
👍
Hi Manuel. Will you be posting the board that uses the magic eye tube as a turn on/off circuit for the module soon. I would like to order them together in one shipment. Thanks for this useful video as my Zenith has a hot chassis.
Yes, they’re on their way to me right now 😊
Nice addition to your Bluetooth lineup Manue, The only trouble is Bluetooth is you can't transmit simultaneously to one's whole radio collection. Coming up with a legal AM transmitter with good audio would be nice for the collector, but offers some serious problems.
True.
Can't vouch for this but there is a seller on ebay (orient100) creating Bluetooth to AM radios supposedly not exceeding 50mW (below the unlicensed limit in most countries). They can trim the frequency to suit. Not cheap, but may be a solution.
Will have a look at it. May be interesting
Hey! Where can I purchase one of those 9v transformers? Thank you!
Depends where you are. I got mine at Mauser.
would it be correct to say using a mains transformer, the dc to dc convertor is no longer needed because you already have isolation /no ground loop (hum) or are you still needing to isolate digital earth from analog earth to prevent digital noise breakthrough?
It is probably not needed with a transformer for that exact reason, but I haven’t experimented with it as yet. Just wanted to see what would be needed to make the same circuit work on a hot chassis.
Greetings From Germany... A question concerning identifying the chassis ground transformer of the radio's schematic and then comparing it to a similar model that has an isolated ground.
Is it possible to make a supplementary video or Part 2 just to show us viewers exactly what to look for on the schematic for a positive identification of chassis ground.
You can easily see it from the schematic. One side of the mains is shown as grounded. You can also just test with a multimeter as I did at the start of the video.
@@electronicsoldandnew I think to remember that you forgot in the schematic to show that one side of the 6.3V filament winding of the transformer is connected to ground. You told it, but it is not drawn. Maybe that is the confusion here ?
Perhaps, but the ground is shown. Not sure I understand the question
When you are stil afraid that the audio ground gets on the live mains, you can put in the soldered audio ground a large capacitor, but it would be a 400V 8µ or so. I don't like the sound of 230V getting in your BT board, it is original not designed for that.
The cap would indeed make it safer, but the mains getting to the board is t a problem as long as it doesn’t get anywhere near anything at a different potential. Effectively all you’re doing is elevating the “ground” reference, which isn’t normally a problem.
There seems to be something wrong with the phono input. Normaly the input is not connected directly to chassis but there is always a block capacity of 5nF to chassis ground. No one would ever sell a construction where you can die by touching the phono inputs.
I’ve seen this before on a jubilate. Dangerous as hell … either by design or some tech changed things in the past.
Why don't you design a circuit so you can't plug it in wrong? Have the circuit flip the hot and neutral the correct way or not allow the radio to have power to the chassis.
I am amazed that the EU never passed a law requiring all member states to standardise on the three-pin mains plug we enjoy here in the UK. 🤣🤣🤣
Yes, that was really realy naughty of me but I hope you get my drift. Here in the UK we're not that clever either with our reversible bayonet mains light sockets. I'd outlaw those as well as it's possible to buy B22 socket extension plugs. ⚡ 👿
I agree with you completely 😊 it would be so easy as some of these plugs have a hole on one end which would only require the sockets to have a protruding pin, but I guess they’re being stubborn in this issue.
@@electronicsoldandnew France and other countries plug have 3 pins, but there is no defined neutral wire position, only the ground/protective one. And you can still use 2 wires plug which you can connect both ways. 3 pin with defined ground is only required for devices with metal cover.
Btw british plug is too big.
Btw Im dissapointed by the design of this little Grundig radio, that there is phono input directly connected to chassis. Standard way for hot chassis radio was to use audio isolation transformer for phono input. Antenna was always protected by small value/high voltage caps (now we call them Y2 caps).
Yes, it’s a pity the plug issue hasn’t been standardised and regulated all over Europe. In Portugal we have no protection as regards mains polarity.
The Grundig was a surprise indeed. Initially I didn’t realise it was an auto transformer, and the worst part was the phono ground to chassis connection. I wonder how many people got shocked over the years … totally needless. A proper transformer would have cost very little more than this one, and all the danger removed from the set.
@@electronicsoldandnew There were planty of hot chassis sets in 40s-50s. Copper was expensive, so transformers were expensive too during war and postwar years.
But I never saw set where you can touch hot chassis without opening back cover. It looks like error.
There is no way how to standardize plugs across Europe - it would be too expensive, you would have to rebuild all electric installation. We in Czech republic also dont have polarized plugs, we use french standard designed in 1920s. German standard doesnt have it too, both wires should be considered as possibly hot.
👍
Why don't you design a circuit so you can't plug it in wrong? Have the circuit flip the hot and neutral the correct way or not allow the radio to have power to the chassis.
That’s not something I care to do, as most people have already found a way to use their radios safely.